#include <bits/stdc++.h>
using namespace std;
set<long long> gera_primos(long long n) {
  set<long long> primos;
  vector<bool> crivo(n + 1);
  primos.insert(2);
  for (long long i = 3; i <= n; i += 2) {
    if (crivo[i]) continue;
    primos.insert(i);
    for (long long j = i; j <= n; j += i) {
      crivo[j] = true;
    }
  }
  return primos;
}
struct Link {
  long long from, to, t;
};
struct Node {
  bool visitado = false;
  set<long long> in, out;
};
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n;
  cin >> n;
  map<long long, long long> d;
  long long ant = 0;
  long long soma = 0;
  for (long long i = 1; i < (long long)1000; i++) {
    long long x = ant + i;
    soma += x;
    if (soma > n) {
      printf("%lld\n", i - 1);
      return 0;
    }
    ant = x;
  }
}
