环形黑白佛珠，黑白相间串最大长度

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();
        StringBuilder sb = new StringBuilder(s);
        sb.append(s);//把原字符串加倍
        int r = 1;
        for(int i = 0; i < sb.length() - 1; ++i){
            int res = 1;
            for(int j = i; j < sb.length() - 1; ++j){//字符a与w的和为217
                if(sb.charAt(j) + sb.charAt(j + 1) == 217) res++;
                else break;
            }
            if(r < res) r = res;
        }
        if(r > s.length()) r = s.length();//原串全部黑白相间，且首尾相异
        System.out.println(r);
    }
}