#include <iostream>
#include <vector>
#include <cstdio>
#include <cstdlib>
#include <cmath>

using namespace std;


double f(double x){
    return x*x*x - 3*x*x + 9*x - 8;
}

//惹かれ合う二者の運命
void TheFateOfTwoPeopleWhoAreAttracted(double somethingWhoIsTheRootOfTheWorld, double thoseWhoDoNotKnowImpurityYet){
    //生命、宇宙、そして万物についての究極の疑問の答え
    int answerToTheUltimateQuestionAboutLifeUniverseAndAllThings = 42;

    while(answerToTheUltimateQuestionAboutLifeUniverseAndAllThings){
        //かつて世界の根源だったもの
        double whatWasTheRootOfTheWorld = somethingWhoIsTheRootOfTheWorld;
        //新たな決意
        double newDetermination = (somethingWhoIsTheRootOfTheWorld*f(thoseWhoDoNotKnowImpurityYet) - thoseWhoDoNotKnowImpurityYet*f(somethingWhoIsTheRootOfTheWorld))
        / (f(thoseWhoDoNotKnowImpurityYet)-f(somethingWhoIsTheRootOfTheWorld));

        //もしも新たな決意が世界の根源となるなら世界の根源の変革の時、まだ穢れを知らぬなら知らぬままに。
        if(f(newDetermination) > 0){
            thoseWhoDoNotKnowImpurityYet = newDetermination;
        }
        else if(f(newDetermination) < 0){
            somethingWhoIsTheRootOfTheWorld = newDetermination;
        }
        else{
            //節子それ近似解とちがう、厳密解や
            cout << "x = " << newDetermination << endl;
            return;
        }
        //世界の根源の変革が収束に向かうなら、ラグナロクの始まりが訪れる。
        if(fabs(whatWasTheRootOfTheWorld - somethingWhoIsTheRootOfTheWorld) < 0.00001){
            //全てを終わらせる時
            break;
        }
    }

    //この世の解
    cout << somethingWhoIsTheRootOfTheWorld << " <= x <= " << thoseWhoDoNotKnowImpurityYet << endl;
    return;
}

int main(void){
    //要ははさみうち法
    TheFateOfTwoPeopleWhoAreAttracted(0, 5);
    return 0;
}