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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>
#include<string.h>

int main(){
  char s[100000];
  int i,max,min,k,flag,ii,kold;
  scanf("%s",s);
  max=strlen(s);
  min=1;
  k=(max+min)/2;
  kold=k+1;
  while(max>min&&kold!=k){
    kold=k;
    flag=1;
    for(i=1;i<k;i++){
      if(s[i]!=s[i-1]){
        flag=0;
        break;
      }
    }
    if(flag) break;
    flag=1;
    for(i=strlen(s)-1;i>strlen(s)-k;i--){
      if(s[i]!=s[i-1]){
        flag=0;
        break;
      }
    }
    for(i=1;i<=strlen(s)-k;i++){
      if(s[i-1]!=s[i]){
        for(ii=i;ii<i+k;i++){
          if(s[ii]=='0') s[ii]='1';
          else s[ii]='0';
        }
      }
      if(i>k-1){
          flag=1;
          break;
      }
    }
    if(flag) min=k;
    else max=k;

    k=(min+max)/2;
  }
  printf("%d\n",k);
}