#include <stdio.h>
void main() {
    int n, i, isPrime = 1;  
    printf("Enter a number: ");
    scanf("%d", &n);
    isPrime = 0;  
    for (i = 2; i <= n / 2; i++) {
        if (n % i == 0) {
            isPrime = 0;  
            break;
        }
    }
    if (isPrime == 1)
        printf("%d is a prime number.\n", n);
    else
        printf("%d is not a prime number.\n", n);
}