题解 | BFS

/*
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 */

#include<bits/stdc++.h>
#include <cctype>
using namespace std;
using i128=__int128;
using u64=unsigned long long;
using u128=unsigned __int128;
#define ll long long 
#define endl '\n'
typedef pair<int,int> PII;
const int MOD=1e9+7;
const int INF=0x3f3f3f3f;
const double eps=1e-4;
void solve(){
    
    string str;
    cin>>str;
    int i;
    for(char& ch:str){
        ch=toupper(ch);
    }
    (i=str.find("BOB"))==string::npos?cout<<-1:cout<<i;
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
	}
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0),cout.tie(0);
	int T=1;
//	cin>>T;
	for(int t=1;t<=T;t++){
		solve();
	}
}