#include<stdio.h>
int main() {
    int n, i;
    unsigned long long factorial = 1;
    printf(" ");
    scanf("%d", &n);
    if (n < 0)
    printf("factorial is not defined for negative numbers.\n");
    else {
        for (i =1; i<= n; ++i) {
            factorial *=i;
        }
        printf(n,factorial);
    }
    return 0;
}