#include <iostream>
#include <queue>
#include <vector>
using namespace std;



int main(){
	int n,start,stop,inf=0x7fffffff,tf=-1;
	cin>>n>>start>>stop;
	int fast[n];
	start--;
	stop--;
	vector<int> v[n];
	queue<int> q;
//	cout<<n<<endl;
	for(int i=0;i<n;i++){
		fast[i]=inf;
		int k;
		cin>>k;
//		cout<<"                                                                            enter:"<<i<<" n:"<<n<<endl;
//		v[i] = new vector<int>();
		v[i].push_back(k+1);
		for(int j=0;j<k;j++){
			int l;
			cin>>l;
			v[i].push_back(l-1);
//		if(n>=39) cout<<"                                                                            enter:j:"<<j<<" k:"<<k<<" n:"<<n<<endl;
		}
	}
	int little=start;
	q.push(start);
	fast[start]=0;
	int len=0;
	while(little != stop   &&   !q.empty()){
		little = q.front();
//		cout<<"little:"<<little<<endl;
		q.pop();
		len = fast[little];
		if(fast[v[little][1]]>len+0){
			fast[v[little][1]] = len+0;
			q.push(v[little][1]);
//			cout<<"    first find:"<<v[little][1]<<endl<<"    len:"<<len<<endl<<endl;
			n--;
			if(q.front()==stop){
				little = stop;
				break;
			}
		}
		int edge_len=v[little][0];
		for(int i=1;i<edge_len;i++){
			if(fast[v[little][i]]>len+1){
				n--;
				fast[v[little][i]] = len+1;
//				cout<<"    second find:"<<v[little][i]<<endl<<"    len:"<<len+1<<endl<<endl;
				if(v[little][i]==stop){
					tf++;
					if(tf){
						little = stop;
						break;
					}
				}
				q.push(v[little][i]);
			}
		}
	}
	if(little==stop  ||  fast[stop]!=inf){
		cout<<fast[stop];
	}
	else{
		cout<<-1;
	}
	return 0;
}

/*
test1, expect 0
================
3 2 1
2 2 3
2 3 1
2 1 2

test2, expect 1
================
4 2 3
3 4 2 3
2 4 3
2 1 4
2 2 3


test3, expect 0
================
4 1 4
3 4 2 3
2 4 3
2 1 4
2 2 3

test4, expect 0
================
4 1 4
3 4 2 3
2 4 3
3 1 4 3
4 2 3 4 4


test5, expect 1
================
4 3 4
4 1 4 2 3
2 4 3
3 1 4 3
4 2 3 4 4

test6, expect 1
================
4 3 2
1 3
2 1 3
2 1 2
2 1 3

test7, expect -1
================
4 3 2
1 3
2 1 3
2 1 4
2 1 3


*/