#include <iostream>
using namespace std;

int main() {
	unsigned long long n;
	cin >> n;
	
	unsigned long long N = 0, bloques = 0;
	
	for(int i = 1; i < 100; i++){
		bloques += i;
		if(bloques > n){
			break;
		}
		N++;
	}
	
	cout << N << "\n";
	
	return 0;
	
}