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 Python (3.4.3) (judge verdict: Time Limit Exceeded)

s=input()
count=1
counted=[]
ans=0
answer_answer=100000000
maxcount=0
if len(s)==1:
  print(1)
else:
    for i in range(1,len(s)):

        if s[i-1]==s[i]:
            count=count+1 
        else:
            counted.append(count)
            count=1
        if i==len(s)-1:
            counted.append(count)            
#    print(counted)
    answer=[]
    answer=counted[:]
    
    if len(counted)==1:
      print(counted[0])
    elif len(counted)==2:
      print(max(counted[0],counted[1]))          
    else:
      while len(answer)>3:
        for i in range(1,len(answer)-1):
            if answer[i-1]+answer[i]+answer[i+1]>=ans: max_i=i
            ans=max(answer[i-1]+answer[i]+answer[i+1],ans)
        
        if max_i!=len(answer)-2 and max_i!=1:
            answer[max_i+1]=answer[max_i+1]+answer[max_i+2]
            answer[max_i-1]=answer[max_i-1]+answer[max_i-2]
            del answer[max_i+2]
            del answer[max_i-2]
            
        elif max_i==len(answer)-2 and max_i!=1:
            answer[max_i-1]=answer[max_i-1]+answer[max_i-2]
            del answer[max_i-2]        
          
        elif max_i!=len(answer)-2 and max_i==1:
            answer[max_i+1]=answer[max_i+1]+answer[max_i+2]
            del answer[max_i+2]           
        
#        print(answer)  
#        print(ans)  
        answer_answer=min(answer_answer,ans)
#    print(answer)
#    print(counted)    
      print(min(answer_answer,answer[0]+answer[1],answer[1]+answer[2]))