#include <cstdio>#include <cstring>#include <iostream>using namespace std;#define re(i,n) for(int i=0;i<n;i++)#define re1(i,n) for(int i=1;i<=n;i++)#define inf (1<<29)const int maxn = 110 , maxm = 10010;int n , m;struct Edge{ int v , w , next;}edge[maxm];int E , head[maxn];inline void init() { E = 0;memset(head,-1,sizeof(head)); }inline void addedge(int u,int v,int w) { edge[E].v=v;edge[E].w=w;edge[E].next=head[u];head[u]=E++; }int dist[maxn];bool mark[maxn];int sta[maxn];int s , t;bool spfa() { int top = 0; memset(mark, false ,sizeof(mark)); re1(i,n) dist[i] = inf; sta[++top] = s; mark[s] = true; dist[s] = 0; while(top) { int u = sta[top--]; mark[u] = false; for(int i=head[u];i!=-1;i=edge[i].next) { int v = edge[i].v; if(dist[v] > dist[u] + edge[i].w) { dist[v] = dist[u] + edge[i].w; if(!mark[v]) { mark[v] = true; sta[++top] = v; } } } } return dist[t] != inf;}int main() { while(~scanf("%d%d%d",&n,&s,&t)) { init(); re1(i,n) { scanf("%d",&m); re(j,m) { int u; scanf("%d",&u); addedge(i,u,(j)?1:0); } } if(spfa()) printf("%dn",dist[t]); else printf("-1n"); } return 0;}
