#include <bits/stdc++.h>
using namespace std;
long long x;
long long factorial(int n) {
  return (n == 1 || n == 0) ? 1 : factorial(n - 1) * n;
}
int main() {
  long long n;
  cin >> n;
  --n;
  cout << factorial(2 * n) / (factorial(n) * factorial(n));
  return 0;
}
