/*
 * Program to compute factorial using loop.
 */
#include <stdio.h>

long fac(int a);

int main(void) {

	int n;
	printf("enter n\n");
	if (scanf("%d", &n) != 1) {
		printf("not number\n");
		return 1;
	}
	printf("fac(%d) is %ld\n", n, fac(n));

	return 0;
}

long fac(int a) {
	long tmp = 1;
	for (int m = 1; m <= a; ++m) {
		tmp *= m;
	}
	return tmp;
}