diff --git a/app/.gitignore b/app/.gitignore
new file mode 100644
index 000000000..42cd73d95
--- /dev/null
+++ b/app/.gitignore
@@ -0,0 +1 @@
+/vendor/
\ No newline at end of file
diff --git a/app/app/BracesChecker.php b/app/app/BracesChecker.php
new file mode 100644
index 000000000..7fec9f6fc
--- /dev/null
+++ b/app/app/BracesChecker.php
@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rmulyukov\Hw4;
+
+final class BracesChecker
+{
+    private array $braces = [];
+
+    public function check(string $braces): bool
+    {
+        if (empty($braces)) {
+            return false;
+        }
+
+        for ($i = 0; $i < strlen($braces); $i++) {
+            if (!$this->handle($braces[$i])) {
+                return false;
+            }
+        }
+        return !$this->hasBraces();
+    }
+
+    private function handle(string $brace): bool
+    {
+        if ($brace === ')') {
+            return $this->removeBrace();
+        }
+        $this->addBrace();
+        return true;
+    }
+
+    private function removeBrace(): bool
+    {
+        if (!$this->hasBraces()) {
+            return false;
+        }
+        array_pop($this->braces);
+        return true;
+    }
+
+    private function addBrace(): void
+    {
+        $this->braces[] = ')';
+    }
+
+    private function hasBraces(): bool
+    {
+        return count($this->braces) > 0;
+    }
+}
diff --git a/app/app/Request.php b/app/app/Request.php
new file mode 100644
index 000000000..6ebe32ece
--- /dev/null
+++ b/app/app/Request.php
@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rmulyukov\Hw4;
+
+final readonly class Request
+{
+    private array $post;
+
+    public function __construct()
+    {
+        $this->post = $_POST;
+    }
+
+    public function get(string $key, string $default = ''): string
+    {
+        $value = $this->post[$key] ?? null;
+        return is_string($value) ? $value : $default;
+    }
+}
diff --git a/app/app/Response.php b/app/app/Response.php
new file mode 100644
index 000000000..a5a88ca88
--- /dev/null
+++ b/app/app/Response.php
@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rmulyukov\Hw4;
+
+final class Response
+{
+    private string $message;
+    private string $header;
+
+    public function __construct(bool $success)
+    {
+        if ($success) {
+            $this->initSuccess();
+        } else {
+            $this->initError();
+        }
+    }
+
+    public function send(): string
+    {
+        header($this->header);
+        return $this->message;
+    }
+
+    private function initSuccess(): void
+    {
+        $this->header = 'HTTP/1.1 200 OK';
+        $this->message = 'OK';
+    }
+
+    private function initError(): void
+    {
+        $this->header = 'HTTP/1.1 400 Bad request';
+        $this->message = 'Incorrect string';
+    }
+}
diff --git a/app/composer.json b/app/composer.json
new file mode 100644
index 000000000..fcd4f5119
--- /dev/null
+++ b/app/composer.json
@@ -0,0 +1,23 @@
+{
+    "name": "rmulyukov/hw4",
+    "type": "project",
+    "authors": [
+        {
+            "name": "Mulyukov Rustyam"
+        }
+    ],
+    "autoload": {
+        "psr-4": {
+            "Rmulyukov\\Hw4\\": "app/"
+        }
+    },
+    "config": {
+        "platform": {
+            "php": "8.2"
+        }
+    },
+    "require": {
+        "php":"^8.2",
+        "ext-memcache": "*"
+    }
+}
diff --git a/app/composer.lock b/app/composer.lock
new file mode 100644
index 000000000..13c60c9e6
--- /dev/null
+++ b/app/composer.lock
@@ -0,0 +1,23 @@
+{
+    "_readme": [
+        "This file locks the dependencies of your project to a known state",
+        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
+        "This file is @generated automatically"
+    ],
+    "content-hash": "af6946a056ec0c28269adbf6afce8d2c",
+    "packages": [],
+    "packages-dev": [],
+    "aliases": [],
+    "minimum-stability": "stable",
+    "stability-flags": [],
+    "prefer-stable": false,
+    "prefer-lowest": false,
+    "platform": {
+        "php": "^8.2"
+    },
+    "platform-dev": [],
+    "platform-overrides": {
+        "php": "8.2"
+    },
+    "plugin-api-version": "2.6.0"
+}
diff --git a/app/public/index.php b/app/public/index.php
new file mode 100644
index 000000000..dc22e8a2a
--- /dev/null
+++ b/app/public/index.php
@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+use Rmulyukov\Hw4\BracesChecker;
+use Rmulyukov\Hw4\Request;
+use Rmulyukov\Hw4\Response;
+
+require_once "../vendor/autoload.php";
+
+$string = (new Request())->get('string');
+$isCorrectString = (new BracesChecker())->check($string);
+echo (new Response($isCorrectString))->send();
diff --git a/docker-compose.yml b/docker-compose.yml
new file mode 100644
index 000000000..8f7b324a3
--- /dev/null
+++ b/docker-compose.yml
@@ -0,0 +1,68 @@
+version: '3.9'
+
+services:
+  nginx-proxy:
+    container_name: proxy-hw4
+    hostname: proxy-hw4
+    build:
+      context: ./docker
+      dockerfile: proxy-nginx/Dockerfile
+    ports:
+      - "8080:80"
+    networks:
+      - hw4-network
+
+  nginx-balancer1:
+    container_name: balancer1-hw4
+    hostname: balancer1-hw4
+    build:
+      context: ./docker
+      dockerfile: balancer-nginx/Dockerfile
+    volumes:
+      - ./app:/hw4/app
+    networks:
+      - hw4-network
+
+  nginx-balancer2:
+    container_name: balancer2-hw4
+    hostname: balancer2-hw4
+    build:
+      context: ./docker
+      dockerfile: balancer-nginx/Dockerfile
+    volumes:
+      - ./app:/hw4/app
+    networks:
+      - hw4-network
+
+  php1:
+    container_name: php1-hw4
+    hostname: php1-hw4
+    build:
+      context: ./docker
+      dockerfile: php/Dockerfile
+    volumes:
+      - ./app:/hw4/app
+    networks:
+      - hw4-network
+
+  php2:
+    container_name: php2-hw4
+    hostname: php2-hw4
+    build:
+      context: ./docker
+      dockerfile: php/Dockerfile
+    volumes:
+      - ./app:/hw4/app
+    networks:
+      - hw4-network
+
+  memcache:
+    container_name: memcache-hw4
+    hostname: memcache-hw4
+    image: memcached:1.6.23-alpine
+    networks:
+      - hw4-network
+
+networks:
+  hw4-network:
+    driver: bridge
\ No newline at end of file
diff --git a/docker/balancer-nginx/Dockerfile b/docker/balancer-nginx/Dockerfile
new file mode 100644
index 000000000..9a78728ca
--- /dev/null
+++ b/docker/balancer-nginx/Dockerfile
@@ -0,0 +1,5 @@
+FROM nginx:1.25.0-alpine
+
+COPY ./balancer-nginx/conf.d /etc/nginx/conf.d
+
+WORKDIR /hw4/app
\ No newline at end of file
diff --git a/docker/balancer-nginx/conf.d/default.conf b/docker/balancer-nginx/conf.d/default.conf
new file mode 100644
index 000000000..b12ac3178
--- /dev/null
+++ b/docker/balancer-nginx/conf.d/default.conf
@@ -0,0 +1,26 @@
+upstream php {
+    server php1-hw4:9000;
+    server php2-hw4:9000;
+}
+
+server {
+    index index.php;
+    root /hw4/app/public;
+
+    location / {
+        try_files $uri $uri/ /index.php?$query_string;
+    }
+
+    location ~ \.php$ {
+        try_files $uri =404;
+        fastcgi_split_path_info ^(.+\.php)(/.+)$;
+        fastcgi_pass php;
+        fastcgi_index index.php;
+        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
+        include fastcgi_params;
+    }
+
+    location ~/\.ht {
+        deny all;
+    }
+}
\ No newline at end of file
diff --git a/docker/php/Dockerfile b/docker/php/Dockerfile
new file mode 100644
index 000000000..dd6ad6d25
--- /dev/null
+++ b/docker/php/Dockerfile
@@ -0,0 +1,16 @@
+FROM php:8.2-fpm-alpine
+
+RUN apk update && apk add --no-cache --virtual .build-temp-deps \
+      autoconf make gcc g++ zlib-dev \
+    && apk update && apk add --no-cache libmemcached-dev \
+    #memcache
+    && pecl install memcache \
+    && docker-php-ext-enable memcache \
+    #composer
+    && curl -sS https://getcomposer.org/installer | php -- --install-dir=/bin --filename=composer --quiet \
+    && rm -rf /root/.composer/cache \
+    && apk del --no-cache -f .build-temp-deps
+
+COPY ./php/conf.d /usr/local/etc/php/conf.d
+
+WORKDIR /hw4/app
\ No newline at end of file
diff --git a/docker/php/conf.d/session.ini b/docker/php/conf.d/session.ini
new file mode 100644
index 000000000..479651ed4
--- /dev/null
+++ b/docker/php/conf.d/session.ini
@@ -0,0 +1,2 @@
+session.save_handler = memcached
+session.save_path = "memcached:11211"
\ No newline at end of file
diff --git a/docker/proxy-nginx/Dockerfile b/docker/proxy-nginx/Dockerfile
new file mode 100644
index 000000000..f07d7a08c
--- /dev/null
+++ b/docker/proxy-nginx/Dockerfile
@@ -0,0 +1,3 @@
+FROM nginx:1.25.0-alpine
+
+COPY ./proxy-nginx/conf.d /etc/nginx/conf.d
\ No newline at end of file
diff --git a/docker/proxy-nginx/conf.d/default.conf b/docker/proxy-nginx/conf.d/default.conf
new file mode 100644
index 000000000..b82019e63
--- /dev/null
+++ b/docker/proxy-nginx/conf.d/default.conf
@@ -0,0 +1,17 @@
+upstream nginx-balancers {
+    least_conn;
+    server balancer1-hw4:80;
+    server balancer2-hw4:80;
+}
+
+server {
+    listen 80;
+
+    location / {
+        proxy_pass http://nginx-balancers;
+    }
+
+    location ~/\.ht {
+        deny all;
+    }
+}
\ No newline at end of file