Luogu_P_1044.cpp

#include <bits/stdc++.h>
using namespace std;
using ui = unsigned int;
ui dfs(ui i, ui j, const ui& n) {
  static vector<vector<ui>> res(n + 1, vector<ui>(n + 1));
  if (res[i][j]) return res[i][j];
  if (i == 0) return res[i][j] = 1;
  res[i][j] = dfs(i - 1, j + 1, n);
  if (j > 0) res[i][j] += dfs(i, j - 1, n);
  return res[i][j];
}
int main(void) {
  ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
  ui n;
  cin >> n;
  cout << dfs(n, 0, n);
  return 0;
}