#include <bits/stdc++.h>
using namespace std;
const int NMax = 1e5 + 5;
const int LIM = 1e5;
int D[100][100];
int main() {
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    D[1][i] = D[i][1] = 1;
  }
  for (int i = 2; i <= n; i++) {
    for (int j = 2; j <= n; j++) {
      D[i][j] = D[i - 1][j] + D[i][j - 1];
    }
  }
  cout << D[n][n];
}
