#include <bits/stdc++.h>

using namespace std;
const double eps = 1e-8;
int main() {
    double x;
    cin >> x;

    double l = -10000, r = 10000;
    while (r - l > eps) {
        double mid = (l + r) / 2; // 注意：浮点数这里不能用右移1位！！
        if (mid * mid * mid > x)
            r = mid; // mid>x后面没有"="
        else
            l = mid;
    }
    printf("%.6lf\n", l);
    return 0;
}