#include <bits/stdc++.h>
using namespace std;
double f(double x)
{
    return 114 * x * x * x - 514 * x * x + 1919 * x - 810;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    double eps = 1e-12;
    double l = 0; // f(l) < 0
    double r = 1; // f(r) > 0
    while (r - l > eps)
    {
        double mid = (l + r) / 2;
        if (f(mid) < 0)
            l = mid;
        else
            r = mid;
    }
    cout << fixed << setprecision(10) << l << "\n";
    return 0;
}