#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;
}
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