Problem:
Score : 500 points

Problem Statement

You are given a string S consisting of 0 and 1.
Find the maximum integer K not greater than |S| such that we can turn all the characters of S into 0 by repeating the following operation some number of times.

Choose a contiguous segment [l,r] in S whose length is at least K (that is, r-l+1\geq K must be satisfied). For each integer i such that l\leq i\leq r, do the following: if S_i is 0, replace it with 1; if S_i is 1, replace it with 0.

Constraints

1\leq |S|\leq 10^5

S_i(1\leq i\leq N) is either 0 or 1.

Input

Input is given from Standard Input in the following format:

S

Output

Print the maximum integer K such that we can turn all the characters of S into 0 by repeating the operation some number of times.

Sample Input 1

010

Sample Output 1

2

We can turn all the characters of S into 0 by the following operations:

Perform the operation on the segment S[1,3] with length 3. S is now 101.

Perform the operation on the segment S[1,2] with length 2. S is now 011.

Perform the operation on the segment S[2,3] with length 2. S is now 000.

Sample Input 2

100000000

Sample Output 2

8

Sample Input 3

00001111

Sample Output 3

4

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
class Program{
	static void Main(){
		string s=Console.ReadLine();
		int ans=s.Length;
		if(s.Length%2==0){
			if(s[s.Length/2-1]!=s[s.Length/2]){ans=s.Length/2;}
			else{
				for(int i=s.Length/2;i<s.Length-1;i++){
					if(s[s.Length-i-1]!=s[s.Length-i-2]||s[i]!=s[i+1]){
						ans=i+1;
						break;
					}
				}
			}
		}
		else if(s.Length!=1){
			if(s[s.Length/2]!=s[s.Length/2-1]||s[s.Length/2]!=s[s.Length/2+1]){ans=s.Length/2+1;}
			else{
				for(int i=s.Length/2+1;i<s.Length-1;i++){
					if(s[s.Length-i-1]!=s[s.Length-i-2]||s[i]!=s[i+1]){
						ans=i+1;
						break;
					}
				}
			}
		}
		Console.WriteLine("{0}",ans);
	}
}