//Find factorial of a number

#include<bits/stdc++.h>
using namespace std;

unsigned long long int factorial(unsigned int number)
{
    if(number<=1)
    {
        return 1;
    }
    unsigned long long int output= number * factorial(number -1);

    return output;
}

int main()
{
    int input;
    cin>>input;

    cout<<factorial(input);
}