#include <bits/stdc++.h>
using namespace std;
long long fact(long long n) {
  long long ret = 1;
  for (long long i = 2; i <= n; i++) ret *= i;
  return ret;
}
long long combinari(long long n, long long k) {
  return fact(n) / fact(k) / fact(n - k);
}
long long n;
int main() {
  cin >> n;
  cout << combinari(2 * (n - 1), (n - 1));
  return 0;
}
