1-1

#include<stdio.h>
int main(void)
{
    int n;
     int factorial(int n);

     scanf("%d",&n);
     printf("%d\n",factorial(n));

     return 0;
}
int factorial(int n)
{
    int i,fact= 1;

    for(i=1;i<=n;i++)
        fact=fact*i;

    return fact;
}