#include <bits/stdc++.h>
using namespace std;
int ele(int row, int col) {
  if (row == 1 || col == 1) return 1;
  return ele(row - 1, col) + ele(row, col - 1);
}
int main() {
  ios_base ::sync_with_stdio(false), cin.tie(NULL), cout.tie(0);
  int i;
  cin >> i;
  cout << ele(i, i);
  return 0;
}
