#include <bits/stdc++.h>
using namespace std;
void inp(int n, int arr[]) {
  for (int i = 0; i < n; i++) cin >> arr[i];
}
int gcd(int a, int b) { return (b == 0) ? a : gcd(b, a % b); }
void solve() {
  int n;
  cin >> n;
  int arr[n][n];
  for (int i = 0; i < n; i++) arr[0][i] = 1;
  for (int i = 0; i < n; i++) arr[i][0] = 1;
  int maxx = arr[0][0];
  for (int i = 1; i < n; i++) {
    for (int j = 1; j < n; j++) {
      arr[i][j] = arr[i][j - 1] + arr[i - 1][j];
      maxx = max(maxx, arr[i][j]);
    }
  }
  cout << maxx << '\n';
}
int main() {
  solve();
  return 0;
}
