#include <bits/stdc++.h>
using namespace std;
int nCn(int n, int r, vector<vector<int>>& dp) {
  if (r == 0 || r == n) return 1;
  if (n == 1) return 1;
  if (dp[n][r] != -1) return dp[n][r];
  dp[n][r] = nCn(n - 1, r - 1, dp) + nCn(n - 1, r, dp);
  return dp[n][r];
}
int main() {
  long long n;
  cin >> n;
  vector<vector<int>> dp(2 * n + 1, vector<int>(n + 1, -1));
  cout << nCn(2 * (n - 1), n - 1, dp);
}
