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>

int n,a[100000]= {0},m;

int fax(int x)
{
    int s=a[0],sum,i;
    for(i=1; i<=m; i++)
    {
        sum=0;
        for(int j=i; j<=m; j++)
        {
            sum+=a[j];
            if(sum>=x)
                break;
        }
        if(sum<x)
            break;
        s+=a[i];
        i++;
        if(s>=x)
            break;
    }
    if(s>=x) return 1;
    else return 0;
}

int main()
{
    char p,c;
    scanf("%c",&c);
    p=c;
    m=0;
    n=0;
    while(c!='\n')
    {
        n++;
        if(p!=c)
            m++;
        a[m]++;
        p=c;
        scanf("%c",&c);
    }
    int mind,left=(n+1)/2,right=n+1,ans=1;
    while(right>left)
    {
        mind=left+(right-left)/2;
        if(fax(mind))
            {
                left=mind+1;
                ans=mind;
            }
        else
            right=mind;
    }
    printf("%d\n",ans);
    return 0;
}