#include <queue>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
using namespace std;
const int MAXN = 105;
const int MAXE = 1000005;
const int inf = 0x3f3f3f3f;
typedef struct _node
{
int v, next, is;
}N;
N edge[2 * MAXE];
int cntEdge, head[MAXN];
typedef struct _no
{
int v;
int dis;
_no(): dis(inf) {}
_no(int a, int b) : v(a), dis(b) {}
friend bool operator < (const struct _no &n1, const struct _no &n2)
{
return n1.dis > n2.dis;
}
}priN;
void init()
{
cntEdge = 0;
for(int i = 0; i < MAXN; i++)
head[i] = -1;
}
void addEdge(int u, int v, int is)
{
edge[cntEdge].v = v;
edge[cntEdge].is = is;
edge[cntEdge].next = head[u];
head[u] = cntEdge++;
}
int dijkstra(int s, int e, int n)//1是起点,n是终点
{
int vst[MAXN] = {0};
int dis[MAXN];
for(int i = 0; i <= n; i++)
dis[i] = inf;
priority_queue<priN> Q;
Q.push(priN(s, 0));
dis[s] = 0;
while(!Q.empty())
{
priN pre = Q.top();
Q.pop();
if(pre.v == e)
return pre.dis;
for(int f = head[pre.v]; f != -1; f = edge[f].next)
{
int son = edge[f].v;
int w = edge[f].is;
if(dis[son] > dis[pre.v] + w)
{
dis[son] = dis[pre.v] + w;
Q.push(priN(son, dis[son]));
}
}
}
return -1;
}
int main(void)
{
#ifndef ONLINE_JUDGE
//freopen("in.txt", "r", stdin);
#endif
int n, s, e;
while(scanf("%d %d %d", &n, &s, &e) == 3)
{
init();
int m, v;
for(int i = 1; i <= n; i++)
{
scanf("%d", &m);
for(int j = 0; j < m; j++)
{
scanf("%d", &v);
addEdge(i, v, (j == 0 ? 0 : 1));
}
}
int sol = dijkstra(s, e, n);
printf("%d\n", sol);
}
return 0;
}