Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

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

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
type Queue struct {
	arr []int
}

func (q *Queue) push(v int) {
	q.arr = append(q.arr, v)
}

func (q *Queue) pop() int {
	res := q.arr[0]
	q.arr = q.arr[1:]
	return res
}

func (q *Queue) isEmpty() bool {
	return len(q.arr) == 0
}

func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	G := make([][]int, N)
	for i := 0; i < N; i++ {
		u, k := sc.nextInt()-1, sc.nextInt()
		for j := 0; j < k; j++ {
			G[u] = append(G[u], sc.nextInt()-1)
		}
	}
	var q Queue
	seen := make([]int, N)
	for i := 0; i < N; i++ {
		seen[i] = -1
	}
	var search func(cur int)
	search = func(cur int) {
		for i := 0; i < len(G[cur]); i++ {
			next := G[cur][i]
			if seen[next] == -1 {
				q.push(next)
				seen[next] = seen[cur] + 1
			}
		}
	}
	q.push(0)
	seen[0] = 0
	for !q.isEmpty() {
		search(q.pop())
	}

	for i := 0; i < N; i++ {
		fmt.Fprintln(wtr, i+1, seen[i])
	}
	wtr.Flush()
}

C++: #include <iostream>
#include <queue>

#define rep(i, n) for (int i = 0; i < (int)(n); ++i)

const int INF = 1 << 21;

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

  int a[n][n];

  rep(i, n) rep(j, n) a[i][j] = 0;

  rep(i, n) {
    int u, k;
    std::cin >> u >> k;
    rep(j, k) {
      int v;
      std::cin >> v;
      a[u - 1][v - 1] = 1;
    }
  }

  int d[n];
  rep(i, n) d[i] = INF;
  d[0] = 0;

  std::queue<int> q;
  q.push(0);

  while (!q.empty()) {
    int u = q.front();
    q.pop();
    rep(j, n) {
      if (a[u][j] && d[j] == INF) {
        d[j] = d[u] + 1;
        q.push(j);
      }
    }
  }

  rep(i, n) std::cout << i + 1 << ' ' << (d[i] == INF ? -1 : d[i]) << '\n';

  return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;

int n,u,k,v;
int g[102][102];
int d[102];
int sn[102];
int cnt=0;
int x,siz;

queue<int>q;

int main(){
  cin>>n;
  memset(g,0,sizeof(g));
  for(int i=1;i<=n;i++){
    cin>>u>>k;
    d[i]=-1;
    sn[i]=0;
    for(int j=1;j<=k;j++){
      cin>>v;
      g[u][v]=1;
    }
  }
  
  q.push(1);

  while(!q.empty()){

    siz=q.size();

    for(int i=0;i<siz;i++){
      
      x=q.front();
      q.pop();
      
      sn[x]=1;
      if(d[x]==-1)d[x]=cnt;
      
      for(int j=1;j<=n;j++){
	
	if(g[x][j]==1 && sn[j]==0){
	  q.push(j);
	}
      
      }

    }

    cnt++;

  }

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

  }

}

C++: #include <stdio.h>
#include <iostream>
using namespace std;

class Adjl{
private:
	int u;
	int k;
	Adjl **next;
	int check_id;
public:
	Adjl(int u);
	~Adjl(){ if (next != NULL) delete[] next; }
	void setV(int k, Adjl *vk);
	int breadthFirstSearch(int id);
	void print(int id);
};

Adjl::Adjl(int u)
{
	this->u = u;
	k = 0;
	next = NULL;
	check_id = 0;
}

void Adjl::setV(int k, Adjl *vk)
{
	if (this->k == 0) next = new Adjl*[k];
	next[this->k] = vk;
	(this->k)++;
}

int Adjl::breadthFirstSearch(int id)
{
	if (id == check_id) return -1;
	else check_id = id;

	if (id == u) {
		check_id = 0;
		return 0;
	}

	for (int i = 0; i < k; i++) {
		if (id == next[i]->u) {
			check_id = 0;
			return 1;
		}
	}
	int d_min = -1;
	for (int i = 0; i < k; i++) {
		int d = next[i]->breadthFirstSearch(id);
		if (d == -1) continue;
		if (d_min == -1) d_min = d + 1;
		else d_min = min(d_min, d + 1);
	}
	check_id = 0;
	return d_min;
}

void Adjl::print(int id)
{
	cout << id << " " << breadthFirstSearch(id) << endl;
}

int main(void)
{
	int n;
	cin >> n;
	
	Adjl **adjl = new Adjl*[n];
	int check[100] = {0};

	for (int i = 0; i < n; i++) {
		int u, k;
		cin >> u >> k;
		if (check[i] == 0) {
			adjl[i] = new Adjl(u);
			check[i] = 1;
		}
		check[i] = 1;
		for (int j = 0; j < k; j++) {
			int vk;
			cin >> vk;
			if (check[vk - 1] == 0) {
				adjl[vk - 1] = new Adjl(vk);
				check[vk - 1] = 1;
			}
			adjl[i]->setV(k, adjl[vk - 1]);
		}
	}

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

	delete[] adjl;
	return 0;
}

C++: #include <stdio.h>
#include <algorithm>

using namespace std;

struct Info{
	Info(){m_node = m_distance = 0;}
	Info(int node,int distance){
		m_node = node;
		m_distance = distance;
	}
	int m_node,m_distance;
};

class InfoQueue{
public:
	InfoQueue(){
		info = new Info[10000];
		num_of_data = head = tail = 0;
	}
	bool isEmpty(){
		return num_of_data == 0;
	}
	void enqueue(Info data){
		info[tail] = data;
		tail = (tail+1)%10000;
		num_of_data++;
	}
	Info dequeue(){
		Info ret = info[head];
		head = (head+1)%10000;
		num_of_data--;
		return ret;
	}
private:
	Info* info;
	int head,tail,num_of_data;
};


int main(){

	int n,row,col,num;
	scanf("%d",&n);

	int table[n+1][n+1];
	int check_table[n+1];

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

	for(int i=1;i<=n;i++){
		scanf("%d %d",&row,&num);
		for(int k=1;k<=num;k++){
			scanf("%d",&col);
			table[row][col]=1;
		}
	}

	check_table[1] = 0;

	InfoQueue Q;
	Q.enqueue(Info(1,0));

	Info tmp;
	while(!Q.isEmpty()){
		tmp = Q.dequeue();
		for(int i=1;i<=n;i++){
			if(table[tmp.m_node][i]==1 && check_table[i] == -1){
				check_table[i] = tmp.m_distance+1;
				Q.enqueue(Info(i,tmp.m_distance+1));
			}
		}
	}

	for(int i=1;i<=n;i++){
		printf("%d %d\n",i,check_table[i]);
	}

    return 0;
}

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

void BFS(vector<vector<int> >& V, vector<int>& time) {
	int i,k;
	int cnt=1;
	queue<pair<int,int> > qv;

	qv.push({1,0});
	time[1]=0;
	while(!qv.empty()) {
		k=qv.front().first;
		cnt=qv.front().second+1;
		qv.pop();
		for(i=0; i<(int)V[k].size(); ++i) {
			if(time[V[k][i]]==-1) {
				qv.push({V[k][i],cnt});
				time[V[k][i]]=cnt;
			}
		}
	}
}

int main() {
	int n,k,u;
	vector<vector<int> > V;
	vector<int> time;

	scanf("%d",&n);
	V.resize(n+1);
	time.resize(n+1);

	for(int i=1; i<=n; ++i) {
		scanf("%d%d",&u,&k);
		V[u].resize(k);
		time[u]=-1;
		for(int j=0; j<k; ++j) {
			scanf("%d",&V[u][j]);
		}
	}
	BFS(V,time);

	for(int i=1; i<=n; ++i) {
		printf("%d %d\n",i,time[i]);
	}
	return 0;
}