#include <iostream>
#include <vector>
#include <algorithm>
#include<string>
#include <cmath>
using namespace std;

int main()
{
    uint64_t x;
    cin >> x;
    uint64_t i = 1, j = 1, a = 1, b = 1;
    uint64_t res = 0;

    while (x)
    {
        if (a <= b)
        {
            x += a == b;
            res = a;
            i += 1;
            a = i*i;
        }
        else
        {
            res = b;
            j += 1;
            b = j*j*j;
        }
        x -= 1;
    }

    cout << res;
    return 0;
}