题解 | BFS

import java.util.Scanner;

public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String str = sc.next();


        for (int i = 0; i < str.length() ; i++) {
            if(i+2 > str.length() -1 ){
                System.out.println("-1");
                break;
            }
        String x = str.substring(i,i+3);
        if(x.equalsIgnoreCase("Bob")){
            System.out.println(i);
            break;
        }
        }
    }
}