#include <bits/stdc++.h>
int main() {
  int n;
  std::cin >> n;
  int a[n][n];
  for (int i = 0; i < n; ++i) {
    a[0][i] = 1;
  }
  for (int i = 0; i < n; ++i) {
    a[i][0] = 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];
  }
  std::cout << a[n - 1][n - 1] << std::endl;
  return 0;
}
