### Problem Statement

A lucky ticket is an integer with exactly 2*n digits (written without leading zeroes), where the sum of the leftmost n digits is equal to the sum of the rightmost n digits.

You are given a String s, which contains only non-zero digits. Find the longest contiguous substring of s that is a lucky ticket and return its length. If there is no such lucky ticket, return 0 instead.

### Definition

 Class: LuckyTicketSubstring Method: maxLength Parameters: String Returns: int Method signature: int maxLength(String s) (be sure your method is public)

### Constraints

-s will contain between 1 and 50 characters, inclusive.
-s will contain non-zero digits ('1'-'9') only.

### Examples

0)

 `"123231"`
`Returns: 6`
 The entire string, 123231, is a lucky ticket because the first 3 digits sum up to 1+2+3=6, and the last 3 digits sum up to 2+3+1=6.
1)

 `"74233285"`
`Returns: 4`
 4233 is the longest lucky ticket here.
2)

 `"986561517416921217551395112859219257312"`
`Returns: 36`
3)

 `"1"`
`Returns: 0`
4)

 `"112"`
`Returns: 2`
 A lucky ticket must contain an even number of digits.

#### Problem url:

http://www.topcoder.com/stat?c=problem_statement&pm=8395

#### Problem stats url:

http://www.topcoder.com/tc?module=ProblemDetail&rd=10802&pm=8395

gevak

#### Testers:

PabloGilberto , Yarin , Olexiy , ivan_metelsky

#### Problem categories:

Simple Search, Iteration