// editor1
#include<stdio.h>
int fact(int m){
    int factorial;
    factorial=n*factorial(n-1);
    return factorial;
}
int main(){
    int n;
    scanf("%d",&n);
    if(n<0){
        printf("Invvalid input");
        return 0;
    }
    fact(n);
    printf("%d ",n);
}