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 <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <ctype.h>

char s[100010];
int buf[100010];
int ind;

int main(void)
{
  int l,run,i,j;
  fgets(s,100010,stdin);
  
  ind = 0;
  l = strlen(s);
  for(i=0;i<l;){
    for(j=i;j<l;j++){
      if(s[i]!=s[j]) break;
    }
    run = j-i;
    buf[ind++] = run;
    i += run;
  }
  int min_sum = 1000000;
  if( ind <= 1 ){
    printf("%d\n",l);
  }else if(ind==2){
    printf("%d\n",(buf[0]>buf[1] ? buf[0] : buf[1]));
  } else {
    int max_idx = -1, max_val = 0;
    for(i=1;i<ind-1;i++){
      if( buf[i]>max_val ){
        max_val = buf[i];
        max_idx = i;
      }
    }
    int len1 = max_val + ( buf[max_idx-1] < buf[max_idx +1] ? buf[max_idx-1] : buf[max_idx+1] );
    int len2 = ( buf[0] > buf[ind-1] ) ? buf[0] : buf[ind-1];
    printf("%d\n", (len1 > len2 ? len1 : len2 ));
  }
  return EXIT_SUCCESS; 
}