#include <iostream>
using namespace std;

class Solution{
public: 
    int factorial(int N){
        if(N == 0){
            return 1;
        }

        int smallOutput = factorial(N - 1);
        int result = N * smallOutput;
        return result;
    }
};

int main() {
    Solution sol;
	int n;
	cin>>n;
    cout << sol.factorial(n) << endl;
    return 0;
}