#include<stdio.h>
int main()
{
    int n,i;
    long factorial=1;
    if(scanf("%d",&n)!=1)
    {
        return 1;
    }
    if(n<0)
    {
        printf("Invalid input");
    }
    else
    {
        for(i=1;i<=n;++i)
        {
            factorial*=i;
        }
        printf("%11d\n",factorial);
    }
    return 0;
}