#define loop(i,from,to) for (int i = from; i < to; ++i)
#include <bits/stdc++.h>

using std::cin;
using std::cout;
using std::endl;
using std::vector;
using std::string;
using std::map;
using std::pair;

const int INF = 1e9+7;
const double eps = 1e-6;

vector<long long> dyn;
long long Ladder(int n) {
  if (n < 1) return 0;
  if (dyn[n] == -1) {
    dyn[n] = 0;
    for (int i = 1; i < n; ++i)
      dyn[n] += Ladder(n - i);
  }
  return dyn[n];
}


signed main() {
  std::ios::sync_with_stdio(false);
  cin.tie(0);
  int n; cin >> n;
  dyn.assign(n + 1, -1);
  dyn[1] = 1;
  cout << Ladder(n);
  //std::cout << "Hello World!\n";
  return 0;
}