#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  vector<vector<int> > a(n + 1, vector<int>(n + 1));
  for (int(i) = 0; (i) < (n + 1); ++(i)) {
    a[i][1] = 1;
    a[1][i] = 1;
  }
  for (int(i) = (2); (i) < (n + 1); i += 1) {
    for (int(j) = (2); (j) < (n + 1); j += 1) {
      a[i][j] = a[i - 1][j] + a[i][j - 1];
    }
  }
  cout << a[n][n] << endl;
  return 0;
}
