#include <bits/stdc++.h>
using namespace std;
int a[20][20];
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) a[i][0] = 1, a[0][i] = 1;
  for (int i = 1; i < n; i++)
    for (int j = 1; j < n; j++) a[i][j] = a[i - 1][j] + a[i][j - 1];
  printf("%d\n", a[n - 1][n - 1]);
  return 0;
}
