// Arup Guha
// 6/21/2023
// Solution to Kattis Problem: Bootstrapping Number
// https://open.kattis.com/problems/bootstrappingnumber
// Illustrates binary search technique

using namespace std;
#include <bits/stdc++.h>

int main() {

    // Get input.
    double n;
    cin >> n;

    // Answer has to be in between 1 and 10.
    double low = 1, high = 10;

    // Fixed number of iterations.
    for (int i=0; i<100; i++) {

        // Go halfway in between.
        double mid = (low+high)/2;

        // mid is too big, reset high to mid.
        if (pow(mid,mid) > n)
            high = mid;

        // Here we are safe resetting low to mid.
        else
            low = mid;
    }

    // Ta da!
    cout << setprecision(9) << low << endl;
    return 0;
}