#include <stdio.h>

int main()
{
	int i, n;

	printf("Enter a number for primality testing: ");
	scanf("%d", &n);

	for (i = 3; i <= i / 2; i = i + 2)
		if ((n % i) == 0)
			break;

	if ((n != 2) && (((n % 2) == 0) || (((n % i) == 0) && (n != i))))
		printf("%d is not a prime\n", n);
	else
		printf("%d is a prime\n", n);
}