#include<stdio.h>

int factorial(int n) {
    if(n == 0 || n == 1)
       return 1;
    return n* factorial(n - 1);
    
}

int main() {
    int n;
    scanf("%d", &n);
    if(n<0 || n>10){
        printf("Invalid input\n");
    }else{
        printf("%d\n", factorial(n))''
    }
    return 0;
}