diff --git a/cmd/shor/main.go b/cmd/shor/main.go
index ee6d2ed..c1a501f 100644
--- a/cmd/shor/main.go
+++ b/cmd/shor/main.go
@@ -26,11 +26,6 @@ func main() {
 		return
 	}
 
-	if number.IsPrime(N) {
-		fmt.Printf("N=%d is prime.\n", N)
-		return
-	}
-
 	if number.IsEven(N) {
 		fmt.Printf("N=%d is even. p=%d, q=%d.\n", N, 2, N/2)
 		return
@@ -41,6 +36,11 @@ func main() {
 		return
 	}
 
+	if number.IsPrime(N) {
+		fmt.Printf("N=%d is prime.\n", N)
+		return
+	}
+
 	if a < 0 {
 		a = rand.Coprime(N)
 	}