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() {
  long long l,x[5]={1,1,1000000,1000000,1},i,ans=0;
  char s[100001];
  scanf("%s",s);
  l=strlen(s);
  for (i=0;i<l&&s[i]==s[i+1];i++) {
    x[0]++;
  }
  for (i=l-1;i>0&&s[i]==s[i-1];i--) {
    x[1]++;
  }
  for (i=x[0]-1;i<l-x[1];i++) {
    if (s[i]==s[i+1]) {
      x[4]++;
    } else if (s[i]=='0') {
      if (x[4]<x[2]) {
        x[2]=x[4];
      }
      x[4]=1;
    } else {
      if (x[4]<x[3]) {
        x[3]=x[4];
      }
      x[4]=1;
    }
  }
  x[3]++;
  x[2]++;
  for (i=0;i<5;i++) {
    if (ans<x[i]&&x[i]!=1000001) {
      ans=x[i];
    }
  }
  printf("%lld\n",ans);
  return 0;
}