/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
    String s="11111";
    int l=s.length();
    double sum=0;
    int t=l-1;
for(int i=0;i<l;i++){   
    int ch=s.charAt(i)-'0';
    int x=(int)ch;
    double d=(Math.pow(2,t-i))*x;
    sum=sum+d;
}
System.out.println(sum);
	}
}

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