#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
int i = 0;
int n = 0;
int ret = 1;
scanf("%d", &n);
for (i = 1; i<=n; i++)
{
ret = ret*i;
}
printf("ret=%d\n", ret);
return 0;
}