#include <stdio.h>

void *stack[1024], **sp = stack;

#define CAT_(a, ...) a ## __VA_ARGS__
#define CAT(...)     CAT_(__VA_ARGS__)
#define GOSUB(lbl)   {*sp++ = &&CAT(L, __LINE__); goto lbl; CAT(L, __LINE__):;}
#define RETURN       goto *--sp

int main(void) {
    int n, f;
    scanf("%d", &n);
    GOSUB(ftp);
    printf("%d", f);
    return 0;

ftp://f...content-available-to-author-only...g.de/
    f = 1;
    https://w...content-available-to-author-only...a.fr/
    if (!n) goto http;
    f *= n--;
    goto https;    
    http://w...content-available-to-author-only...s.ru/
    RETURN;
}