#include<stdio.h>

#include<math.h>

int Facl(int n)

{

int i = 0;

int ret = 1;

for (i = 1; i <= n; i++)

{

 ret = ret * i;

}

return ret;

}

int main()

{

int n = 0;

int ret = 0;

scanf("%d\n", &n);

ret = Facl(n);

printf("ret=%d\n", ret);

return 0;

}