60pts求助

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll n,a,b,vis[10001],dis[10001],y,x;
queue<ll>q;
vector<ll>g[10001];
int main(){
	cin>>n>>a>>b;
	for (ll i=1;i<=n;i++){
		cin>>x;
		while (x--){
			cin>>y;
			g[i].push_back(y);
		}
	}
	fill(dis,dis+n+1,2147483647);
	q.push(a);
	vis[a]=1;
	dis[a]=0;
	while (q.size()){
		ll cur=q.front();
		q.pop();
		vis[cur]=0;
		for(ll i=0;i<g[cur].size();i++){
			ll now=g[cur][i];
			if (dis[cur]+1<dis[now]){
				dis[now]=dis[cur]+1;
				if (vis[now]==0){
					vis[now]=1;
					q.push(now);
				}
			}
		}
	}
	if (dis[b]!=2147483647) cout<<dis[b]-1;
	else cout<<-1;
}