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