MERGSORT

       IDENTIFICATION DIVISION.
       PROGRAM-ID. ISORT.
       ENVIRONMENT DIVISION.
       INPUT-OUTPUT SECTION.
       FILE-CONTROL.
           SELECT INPUT1 ASSIGN TO INP1.
           SELECT INPUT2 ASSIGN TO INP2.
           SELECT OUTPUT1 ASSIGN TO OUT.
           SELECT WORK ASSIGN TO WRK.
       DATA DIVISION.
       FILE SECTION.
       FD INPUT1.
       01 INPUT1-CUSTOMER.
                05 CUSTOMER-ID-I1 PIC 9(5).
                05 CUSTOMER-NAME-I1 PIC A(25).
       FD INPUT2.
       01 INPUT2-CUSTOMER.
                05 CUSTOMER-ID-I2 PIC 9(5).
                05 CUSTOMER-NAME-I2 PIC A(25).
       FD OUTPUT1.
       01 OUTPUT-CUSTOMER.
          05 CUSTOMER-ID-O PIC 9(5).
          05 CUSTOMER-NAME-O PIC A(25).
       SD WORK.
       01 WORK-CUSTOMER.
          05 CUSTOMER-ID-W PIC 9(5).
          05 CUSTOMER-NAME-W PIC A(25).
       PROCEDURE DIVISION.
           MERGE WORK ON ASCENDING KEY CUSTOMER-ID-W
            USING INPUT1, INPUT2 GIVING OUTPUT1.
            DISPLAY 'SORT AND MERGE SUCESSFUL'.
            STOP RUN.