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.

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.

Constraints

• $1\leq |S|\leq 10^5$
• $S_i(1\leq i\leq N)$ is either 0 or 1.

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

见题面 Input 部分

见题面 Output 部分