Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func main() {
	scn := bufio.NewScanner(os.Stdin)
	scn.Split(bufio.ScanWords)
	nextInt := func() int { scn.Scan(); r, _ := strconv.Atoi(scn.Text()); return r }
	w := bufio.NewWriter(os.Stdout)

	n := nextInt()
	vecs := make([][]int, n)
	for i := 0; i < n; i++ {
		u := nextInt()
		k := nextInt()
		for j := 0; j < k; j++ {
			vecs[u-1] = append(vecs[u-1], nextInt()-1)
		}
	}

	ds := make([]int, 0, n)
	for i := 0; i < n; i++ {
		ds = append(ds, -1)
	}

	q := make([]int, 0, n)
	q = append(q, 0)
	ds[0] = 0

	for len(q) > 0 {
		i := pop(&q)
		for _, v := range vecs[i] {
			if ds[v] == -1 {
				ds[v] = ds[i]+1
				q = append(q, v)
			}
		}
	}

	for i, d := range ds {
		fmt.Fprintln(w, i+1, d)
	}

	w.Flush()
}

func pop(q *[]int) int {
	v := (*q)[0]
	*q = (*q)[1:]
	return v
}

C++: #include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#define white 0
#define black -1
#define grey 1
#define infly 1<<21
using namespace std;
int a[110][110],n;
int d[110];
int color[110];

void bfs()
{
    memset(d,0,sizeof(d));
    queue<int> Q;
    for(int i=1;i<=n;i++)
        d[i]=infly;
    d[1]=0;
    for(int i=1;i<=100;i++)
        color[i]=white;
    Q.push(1);
    while(!Q.empty())
    {
        int u=Q.front();
        Q.pop();
        for(int i=1;i<=n;i++)
        {
            if(a[u][i]==0)
                continue;
            if(d[i]!=infly)
                continue;
                Q.push(i);
                d[i]=d[u]+1;
        }
    }
    for(int i=1;i<=n;i++)
   {
       cout<<i<<" "<<((d[i]==infly)?(-1):d[i])<<endl;
   }

}

int main()
{
   int key,d,x;
   memset(a,0,sizeof(a));
   scanf("%d",&n);
   for(int i=1;i<=n;i++)
   {
       scanf("%d%d",&key,&d);
       for(int j=1;j<=d;j++)
       {
        scanf("%d",&x);
        a[key][x]=1;
       }
   }
   bfs();
   return 0;
}

C++: //16D8103013E Sen Shunkou
#include<iostream>
#include<queue>
int n;
int cnt=0;

int main(){
    //input
    int n;
    std::cin>>n;

    int cnt=0;
    int A[100][100];
    int dis_min[n];
    bool visited[n];

    for(int i=0;i<n;i++){
        for(int j=0;j<n;j++){
            A[i][j]=0;
        }
    }

    for(int i=0;i<n;i++){
        std::cin>>A[i][0];
        std::cin>>A[i][1];
        for(int j=0;j<A[i][1];j++){
            std::cin>>A[i][j+2];
        }
    }

    for(int i=0;i<n;i++){
        dis_min[i]=-1;
    }

    //initialization
    std::queue<int> que;
    que.push(0);
    //std::cout<<"\n"<<que.front()<<"\n";
    //std::cout<<que.size()<<"\n\n";

    while(!que.empty()){
        int q=que.size();
        for(int k=0;k<q;k++){
            //std::cout<<"quesize"<<que.size()<<"\n";
            int i=que.front();
            que.pop();
            visited[i]=true;
            dis_min[i]=cnt;
            //std::cout<<i<<"cnt"<<cnt<<"\n";
            if(A[i][1]!=0){
                for(int j=0;j<A[i][1];j++){
                    if(visited[A[i][j+2]-1]!=true){
                        visited[A[i][j+2]-1]=true;
                        que.push(A[i][j+2]-1);
                        //std::cout<<A[i][j+2]-1<<"\n";
                    }
                }
            }
        }
        cnt++;
        //std::cout<<"cnt="<<cnt<<"\n";
    }

    //std::cout<<"===========\n";
    for(int i=0;i<n;i++){
        std::cout<<i+1<<" "<<dis_min[i]<<std::endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define INFTY (1<<30)

int n;
vector<vector<int>> M(101,vector<int>(101,0));
vector<int> color(101,0),d(101,INFTY);
queue<int> Q;

void bfs(){
    color[1]=1;
    d[1]=0;
    Q.push(1);
    while(!Q.empty()){
        int u=Q.front();
        Q.pop();
        for(int v=1;v<n+1;v++){
            if(M[u][v]&&color[v]==0){
                color[v]=1;
                d[v]=d[u]+1;
                Q.push(v);
            }
        }
        color[u]=2;
    }
}


int main(){
    cin>>n;
    for(int i=0;i<n;i++){
        int a,b,k;
        cin>>a>>k;
        for(int j=0;j<k;j++){
            cin>>b;
            M[a][b]=1;
        }
    }

    bfs();

    for(int i=1;i<n+1;i++){
        cout<<i<<' ';
        if(d[i]==INFTY) cout<<-1<<endl;
        else cout<<d[i]<<endl;
    }
}

C++: #include<iostream>
#include<vector>
#include<algorithm>
#include<cmath>
#include<ctime>
#include<queue>

using namespace std;
using ll = long long;

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  int ti = clock();
  // start-----------------------------------------------
  int n; cin >> n;
  vector<vector<int>> g(n);
  for(int i = 0; i < n; i++){
    int u, k;
    cin >> u >> k;
    u--;
    for(int j = 0; j < k; j++){
      int v; cin >> v; v--;
      g[u].push_back(v);
    }
  }
  vector<int> dist(n, -1);
  queue<int> q;
  q.push(0);
  dist[0] = 0;
  while(!q.empty()){
    int now = q.front();
    q.pop();
    for(int nx: g[now]){
      if(dist[nx] == -1){
        dist[nx] = dist[now] + 1;
        q.push(nx);
      }
    }
  }
  for(int i = 0; i < n; i++) cout << i+1 << ' ' << dist[i] << endl;
  // end-----------------------------------------------
  // cerr << 1.0 * (clock() - ti) / CLOCKS_PER_SEC << endl;
}

C++: #include<iostream>
#include<vector>
#include<queue>
using namespace std;

void InputSet(std::vector<int> & a) {
	int n;
	cin >> n;
	a.resize(n,0);
	for(int i=0;i<n;++i) {
		cin >> a.at(i);
		a.at(i)--;
	}
}
void BFS(vector<vector<int> > & Ad,
		 vector<int> & V,
		 queue<int> & Q
		 )
{
	while(!Q.empty()) {
		int u = Q.front();
		Q.pop();
		for(int i=0;i<(int)Ad[u].size();++i) {
			int next = Ad[u][i];
			if (V[next] < 0) {
				V[next] = V[u] + 1;
				Q.push(next);
			}
		}
	}
}
int main(){
	int n;
	cin >> n;
	vector<vector<int> > Ad(n);
	vector<int> V(n,-1);
	queue<int> Q;
	for(int k=0;k<n;++k) {
		int u;
		cin >> u;
		--u;
		InputSet(Ad[u]);
	}
	Q.push(0);
	V[0]=0;
	BFS(Ad,V,Q);

	for(int i=0;i<n;++i){
		cout << i + 1 << " " << V[i] << endl;
	}
}

C++: //
#if 0

#endif // 0
#include<iostream>
#include<queue>
#define MAX 100
using namespace std;
int matri[MAX][MAX];

int main()
{
    int n;
    int r[MAX];
    queue<int> q;
    cin>>n;
    for(int i=0;i<n;i++)
    {
        r[i]=0;
        for(int j=0;j<n;j++)
            matri[i][j]=0;
    }
    for(int i=0;i<n;i++)
    {
        int u,k;
        cin>>u>>k;
        for(int j=0;j<k;j++)
        {
            int m;
            cin>>m;
            matri[u-1][m-1]=1;
        }
    }
    q.push(0);
    r[0]=0;
    while(!q.empty())
    {
        int t;
        t=q.front();
        q.pop();
        for(int i=0;i<n;i++)
            if(matri[t][i]&&r[i]==0&&i)
            {
                q.push(i);
                r[i]=r[t]+1;
               // cout<<r[i]<<endl;
            }
    }
    for(int i=0;i<n;i++)
    {
        if(r[i]||r[i]==i)
            cout<<i+1<<" "<<r[i]<<endl;
        else
            cout<<i+1<<" -1"<<endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
#include <bits/stdc++.h>
#define r(i,a,n) for(int i=a;i<n;i++)
using namespace std;
int a[101][101],start[101],end[101],n,p=0,v[101];
queue<int> q;
void bfs(int u){
	q.push(u);
	v[u]++;
	while(!q.empty()){
		u=q.front();q.pop();
		r(i,1,n+1)if(!v[i]&&a[u][i]){
			v[i]++;
			q.push(i);
			start[i]=start[u]+1;
		}
	}
}
int main(){
	int q,qq,qqq;
	cin>>n;
	r(i,0,n){
		cin>>q>>qq;
		r(i,0,qq){
			cin>>qqq;
			a[q][qqq]++;
		}
	}
	bfs(1);
	r(i,1,n+1){
		if(i!=1&&start[i]==0)cout<<i<<' '<<-1<<endl;
		else cout<<i<<' '<<start[i]<<endl;
	}
}