text: #include<iostream>
  
  using namespace std;
  
  int main(){
      ios_base::sync_with_stdio(false);
      cin.tie(NULL);
  
      long long input, compare = 1;
      long long index = 1;
      cin >> input;
      while(input > compare){
          compare += index * 6;
          index++;
      }
      cout << index;
  
      return 0;
  }