#include <bits/stdc++.h>
using namespace std;
int a[40][40];
int n;
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      if (i == 1 || j == 1) {
        a[i][j] = 1;
      } else {
        a[i][j] = a[i - 1][j] + a[i][j - 1];
      }
    }
  }
  cout << a[n][n] << endl;
  ;
  return 0;
}
