#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int ans = 0, last = 0, current = 0;
  while (n > 0) {
    ans++;
    current = last + ans;
    last = current;
    n -= current;
    if (n < 0) {
      ans--;
    }
  }
  cout << ans;
}
