#include <bits/stdc++.h>
using namespace std;
int m[100][100];
int main(int argc, char const *argv[]) {
  ios_base::sync_with_stdio(0);
  long n, suma = 0;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      m[i][j] = 1;
    }
  }
  for (int i = 1; i < n; ++i) {
    for (int j = 1; j < n; ++j) {
      int x = m[i - 1][j], y = m[i][j - 1];
      m[i][j] = x + y;
    }
  }
  cout << m[n - 1][n - 1] << endl;
  return 0;
}
