#include <bits/stdc++.h>
using namespace std;
signed long long int d[102][102];
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];
}
