#include <bits/stdc++.h>
using namespace std;
int main() {
  long a[101][101], n;
  cin >> n;
  for (long i = 0; i < n; i++) a[i][0] = a[0][i] = 1;
  for (long i = 1; i < n; i++)
    for (long j = 1; j < n; j++) a[i][j] = a[i][j - 1] + a[i - 1][j];
  cout << a[n - 1][n - 1];
  return 0;
}
