#include <bits/stdc++.h>
using namespace std;
vector<long long> v;
int main() {
  long long n;
  cin >> n;
  long long f[n][n];
  for (int j = 1; j < n; j++) {
    f[0][j] = 1;
  }
  for (int j = 0; j < n; j++) {
    f[j][0] = 1;
  }
  for (int i = 1; i < n; i++) {
    for (int j = 1; j < n; j++) {
      f[i][j] = f[i - 1][j] + f[i][j - 1];
    }
  }
  cout << f[n - 1][n - 1];
}
