//  Data Structures with Java by John R. Hubbard
//  Copyright McGraw-Hill, 2001
//  Problem 1.10 on page 21


public class Pr0110
{ public static void main(String[] args)
  { System.out.println("binaryToUnsigned(\"010100001001\") = "
      + binaryToUnsigned("010100001001"));
    System.out.println("binaryToUnsigned(\"101011110111\") = "
      + binaryToUnsigned("101011110111"));
  }
  
  public static int binaryToUnsigned(String code)
  { int n = code.length();
    int answer = 0;
    for (int i=0; i<n; i++)
      answer = answer*2 + (code.charAt(i)=='1' ? 1 : 0);
    return answer;
  }
}