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

int bisect(float a, float b, float p);
int f(float x);

int main(void)
{
    float x1, x2;
    float p, ans;

    x1 = 0;
    x2 = 100;

    scanf("%f", &p);
    ans = bisect(x1, x2, p);
    printf("%f", ans);

    return(0);

}

int bisect(float a, float b, float p)
{
    float c;
    c = (a-b)/2;

    if (abs(a-b) > 2*p)
    {
        return(c);
    }

    else if(f(a)*f(c) < 0)
    {
        return(bisect(a,c,p));
    }
    else if(f(b)*f(c) < 0)
    {
        return(bisect(c, b, p));
    }
    else
    printf("midpoint is exacly on the root");

}

int f(float x)
{
    float func;
    func = ((x-sqrt(3))*(x+x+1));
    return(func);
}