#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  vector<vector<int> > a(n, vector<int>(n));
  for (int i = 0; i < n; i++) a[i][0] = 1, a[0][i] = 1;
  for (int i = 1; i < n; i++) {
    for (int j = 1; j < n; j++) {
      a[i][j] = a[i][j - 1] + a[i - 1][j];
    }
  }
  cout << a[n - 1][n - 1] << endl;
  return 0;
}
