#include <stdio.h>

int factorial(int);

int main(void) {
    int input;
    scanf("%d", &input);

    int f = factorial(input);

    printf("%d", input);
    printf("! = ");
    printf("%d", f);

    putchar('\n');

    return 0;
}

int factorial(int n) {

    int retval;

    if (n == 0) goto factorial__n_eq_0;

    retval = n * factorial(n - 1);
    goto factorial__epilogue;


factorial__n_eq_0:
    retval = 1;

factorial__epilogue:
    return retval;



}