Go: package main

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

//util
var sc = bufio.NewScanner(os.Stdin)

func nextStr() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func printList(list []int) {
	n := len(list)
	buf := bufio.NewWriter(os.Stdout)
	for _, v := range list[0 : n-1] {
		buf.Write([]byte(fmt.Sprintf("%d ", v)))
	}
	buf.Write([]byte(fmt.Sprintf("%d\n", list[n-1])))
	buf.Flush()
}

func max(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func min(a, b int) int {
	if a > b {
		return b
	} else {
		return a
	}
}

//solve
const INFTY = (1 << 21)
const MAX = 100
const WHITE = 0
const GRAY = 1
const BLACK = 2

var time, n int

//隣接行列
var M [MAX][MAX]int

//d[i]: 頂点1から頂点iまでの距離
var color, d [MAX]int

func bfs(s int) {
	var q []int
	q = append(q, s)
	for i := 0; i < n; i++ {
		d[i] = INFTY
	}
	//sは開始点なので、0をいれる
	d[s] = 0

	//キューが空になるまで、以下を繰り返す
	for len(q) > 0 {
		u := q[0]
		q = q[1:]
		for v := 0; v < n; v++ {
			if M[u][v] == 0 {
				continue
			}
			if d[v] != INFTY {
				continue
			}
			d[v] = d[u] + 1
			q = append(q, v)
		}
	}

	for i := 0; i < n; i++ {
		fmt.Printf("%d ", i+1)
		if d[i] == INFTY {
			fmt.Printf("%d\n", -1)
		} else {
			fmt.Printf("%d\n", d[i])
		}
	}
}

func main() {
	sc.Split(bufio.ScanWords)
	n = nextInt()
	for i := 0; i < n; i++ {
		u, k := nextInt(), nextInt()
		M[u-1][u-1] = 0

		//fmt.Println(u, k)
		if k > 0 {
			for j := 0; j < k; j++ {

				v := nextInt()
				M[u-1][v-1] = 1

			}
		}

	}

	bfs(0)

}

C++: #include<stdio.h>
 
 
int G[101][101], q1[101], q2[101], n;
 
void f(int a, int b){
  int i;
  q1[a] = b;
  for(i = 1; i <= q2[a]; i++){
    if(b + 1 < q1[G[a][i]]) f(G[a][i], b + 1);
  }
}
 
int main(){
  int i, j, m;
 
  scanf("%d", &n);
 
  for(i = 1; i <= n; i++){
    q1[i] = 100000000;
    scanf("%d", &m);
    scanf("%d", &q2[m]);
 
    for(j = 1; j <= q2[m]; j++) scanf("%d", &G[m][j]);
  }
 
  f(1, 0);
 
  for(i = 1; i <= n; i++){
    if(q1[i] == 100000000) q1[i] = -1;
  }
 
  for(i = 1; i <= n; i++) printf("%d %d\n", i, q1[i]);
 
  return 0;
}

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;
	}
}