#include <iostream>
using namespace std;

int main() {
    double accu = 1e-3;
    double l = -20, r = 20;
    double x;
    cin >> x;
    double mid = 0;
    while (abs(r - l) > accu) { // 注意 while 处理多个 case
        mid = (l + r) / 2;
        if (mid * mid * mid < x)l = mid;
        else r = mid;
    }
    printf("%.1lf\n", mid);
}
// 64 位输出请用 printf("%lld")