f(x)=y

#include<iostream>
#include <math.h>
#include <conio.h>
using namespace std;
float y;
float f(float x)
{ return sin(x)+sin(2*x)+x;
}

float DEI(float s, float d)
{
   if(d-s<=0.0000001) return s;
   else
   { float m=(s+d)/2;
     if(f(m)==y) return m;
     else if(f(m)<y) return DEI(m,d);
          else return DEI(s,m);
   }
}

int main()
{
    cin>>y;
    cout.precision(8);
    cout<<DEI(0,1);
//  system("pause");
    getch();
  return 0;
}