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 Go (1.6) (judge verdict: Wrong Answer)

package main

import (
	"bufio"
	"fmt"
	"io"
	"math"
	"os"
	"strconv"
	"strings"
)

func main() {
	solve(os.Stdin, os.Stdout)
}

func solve(in io.Reader, out io.Writer) {
	bs := NewBufScanner(in)
	bw := NewBufWriter(out)
	defer bw.w.Flush()
	s := bs.Scan()
	slice := strings.Split(s, "")
	minCount := math.MaxInt32

	i := 0
	for {
		count, next := getLength(slice[i:])
		i = next + i
		if count < minCount {
			minCount = count
		}
		if i + 1 >= len(slice) {
			break
		}
	}

	bw.Printf("%v", minCount)
}

func getLength(s []string) (int, int) {
	start := s[0]
	isSwitch := false
	count := 1
	next := len(s)
	for i, c := range s[1:] {
		if start == c {
			count++
		} else {
			if isSwitch {
				next = i + 1
				count++
				break
			} else {
				if count == 1 {
					isSwitch = true
					start = c
				} else {
					next = i + 1
					break
				}
			}
		}
	}

	return count, next
}

// BufScanner original scanner
type BufScanner struct {
	s *bufio.Scanner
}

// NewBufScanner constructer
func NewBufScanner(in io.Reader) *BufScanner {
	s := bufio.NewScanner(in)
	s.Buffer(make([]byte, 1024), 1e+9)
	s.Split(bufio.ScanWords)
	return &BufScanner{
		s: s,
	}
}

// Scan Scan Data
func (b *BufScanner) Scan() string {
	b.s.Scan()
	return b.s.Text()
}

// IntScan Scan Data
func (b *BufScanner) IntScan() int {
	v, err := strconv.Atoi(b.Scan())
	if err != nil {
		panic(err)
	}
	return v
}

// BufWriter original writer
type BufWriter struct {
	w *bufio.Writer
}

// NewBufWriter constructer
func NewBufWriter(out io.Writer) *BufWriter {
	w := bufio.NewWriter(out)
	return &BufWriter{
		w: w,
	}
}

// Printf Output file
func (b *BufWriter) Printf(format string, a ...interface{}) {
	fmt.Fprintf(b.w, format, a...)
}