#include <stdio.h>

/*
    获取n的阶乘 注意这个返回值要为long long不然会精度不够
*/
long long factorial(int n){
    if(0 == n || 1 == n){
        return 1;
    }
    return n * factorial(n - 1);
}



int main() {
    int n;
    while (scanf("%d", &n) != EOF) { // 注意 while 处理多个 case
        printf("%lld\n", factorial(n));
    }
    return 0;
}