#include <bits/stdc++.h>
using namespace std;
void maxi() {
  long long int n;
  cin >> n;
  long long int a[n][n];
  for (long long int i = 0; i < n; i++) {
    for (long long int j = 0; j < n; j++) {
      if (i == 0 || j == 0) {
        a[i][j] = 1;
      } else {
        a[i][j] = a[i - 1][j] + a[i][j - 1];
      }
    }
  }
  cout << a[n - 1][n - 1] << endl;
}
int main() {
  maxi();
  return 0;
}
