URI 1156 Solution

#include <iostream>

#include<iomanip>

using namespace std;

int main()

{

    double S=0.00;

    double j=1.0;

    for(double i=1;i<=39;i+=2)

    {

      S += i/j;

      j *=2;

    }

    cout<<setprecision(3)<<S<<endl;

    return 0;

}