#include <bits/stdc++.h>
using namespace std;
int f(int x, int y) {
  if (x == 1 || y == 1)
    return 1;
  else
    return f(x - 1, y) + f(x, y - 1);
}
int main() {
  int n;
  while (cin >> n) {
    cout << f(n, n) << endl;
  }
  return 0;
}
