#include <iostream>
using namespace std;
int main()
{
unsigned long long n,sum;
cin >> n;
sum = n*(n-1)/2*(n-2)/3*(n-3)/4;
cout << sum << endl;
return 0;
}
#include <iostream>
using namespace std;
int main()
{
unsigned long long n,sum;
cin >> n;
sum = n*(n-1)/2*(n-2)/3*(n-3)/4;
cout << sum << endl;
return 0;
}