#include <bits/stdc++.h>

using namespace std;

long long n;

long long calcu();

int main()
{
	cin >> n;
	cout << calcu();
	return 0;
}

long long calcu()
{
	long long low, high, mid;
	
	low = 1;
	high = n;
	while(low <= high)
	{
		mid = (low + high) / 2;
		if(mid * mid * mid <= n)//(low - 1)的三次方 <= n 
		{
			low = mid + 1;
		}
		if(mid * mid * mid > n) 
		{
			high = mid - 1;
		}
	}
	return low - 1;
}