#include <stdio.h>
#include <math.h>

double func(double x){
//    return tan(x) - 4.0/3.0;
    return x*x+2.0*x+0.999999;
}

int step = 0;

/*
 Find x | func(x)=0, x1 < x < x2 by bisection_method.
 func(x) must be monotonic increasing in interval [x1, x2] and
 satisfies func(x1) < 0 and func(x2) > 0.
 acc is accuracy of the solution.
 */
double bisection_method(double x1, double x2, double acc){
    double mid = (x1+x2)/2.0;
    double fmid = func(mid);
    
    step++;
    printf("step:%d %lf %lf\n", step, x1, x2);
    
    if(fabs(fmid) < acc) return mid;
    else if(fmid < 0) return bisection_method(mid, x2, acc);
    else return bisection_method(x1, mid, acc);
}

int main(){
    double x1, x2;
    scanf("%lf %lf", &x1, &x2);
    printf("%lf\n", bisection_method(x1, x2, 0.000001));
    return 0;
}