#include <bits/stdc++.h>
using namespace std;
int solve(int i, int j) {
  if (i == 1 || j == 1)
    return 1;
  else
    return solve(i - 1, j) + solve(i, j - 1);
}
int main() {
  int n;
  scanf("%d", &n);
  printf("%d\n", solve(n, n));
  return 0;
}
