#include <bits/stdc++.h>
using namespace std;
const int EPS = 1e-6;
const int INF = (int)(INT_MAX - 100);
const long long mod = (int)(1e+9 + 7);
const int N = (int)(0);
int main() {
  int n;
  cin >> n;
  int t[n][n];
  for (int it = 0; it < n; it++) {
    t[it][0] = 1;
    t[0][it] = 1;
  }
  for (int f = (1); f <= (n - 1); f++) {
    for (int c = (1); c <= (n - 1); c++) {
      t[f][c] = t[f - 1][c] + t[f][c - 1];
    }
  }
  cout << t[n - 1][n - 1];
  return 0;
}
