#include<stdio.h>
int main(){
    int n;
    long long factorial = 1;
    scanf("%d", &n);
    if(n < 0){
        printf("Invalid input\n");
    } else {
        for(int i = 1; i <= n; i++){
            factorial *= i;
        }
        printf("11d\n", factorial);
    }
    return 0;
}