#include <bits/stdc++.h>
using namespace std;
long long int a[20][20];
int main() {
  long long int n, i, j, k;
  cin >> n;
  for (i = 1; i <= n; i++) {
    a[i][1] = 1;
    a[1][i] = 1;
  }
  long long int ans = 1;
  for (i = 1; i <= n; i++)
    for (j = 1; j <= n; j++) {
      if (i != 1 || j != 1) {
        a[i][j] = a[i - 1][j] + a[i][j - 1];
        ans = max(ans, a[i][j]);
      }
    }
  cout << ans << endl;
}
