题解 | BFS

#include<bits/stdc++.h>
using namespace std;


int main(){
	string s;
	cin>>s;
	transform(s.begin(),s.end(),s.begin(),::toupper);//或者tolower 
	
	if(s.find("BOB")==-1){
		cout<<"-1"<<endl;
	}else{
		cout<<s.find("BOB")<<endl;
	}

    return 0;
}