#include <bits/stdc++.h>
using namespace std;
bool isPowerOf2(long long int num) { return (num && (!(num & (num - 1)))); }
int main() {
  int n = 0;
  cin >> n;
  std::vector<std::vector<int>> arr(n, std::vector<int>(n, 1));
  int i = 0, j = 0, ma = 1;
  for (i = 1; i < n; i++) {
    for (j = 1; j < n; j++) {
      arr[i][j] = arr[i - 1][j] + arr[i][j - 1];
      ma = max(ma, arr[i][j]);
    }
  }
  cout << ma << endl;
  return 0;
}
