#include <stdio.h>
#include <stdlib.h>
int main(void) 
{
	int n,i=1,fact=1;
	
	do
	{
		scanf("%d",&n);
		printf("input n(n>0):%d\n",n);
	}
	while(n<=0);
	
	do
		fact*=i++;
	while (i <= n);
	printf("%d!=%d\n",n,fact);
	
	return 0;
}