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++: //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<100;i++){
        for(int j=0;j<100;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";

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

    return 0;
}

C++: #include<iostream>
#include<vector>
#include<cstring>
#include<queue>
#define P pair<int, int>

using namespace std;

int n, d[109];
vector<int> G[109];
bool check[109];


int main(){
  cin >> n;
  for(int i=0;i<n;i++){
    int u, k, v;
    cin >> u >> k;
    for(int i=0;i<k;i++){
      cin >> v;
      G[u].push_back(v);
    }
  }
  memset(check, false, sizeof(check));
  memset(d, -1, sizeof(d));
  queue<P> Q;
  Q.push(P(1, 0));
  check[1]=true;
  while(!Q.empty()){
    P p = Q.front();Q.pop();
    int n=p.first, dis = p.second;
    d[n] = dis;
    for(int i=0;i<G[n].size();i++){
      if(!check[G[n][i]]){
        check[G[n][i]]=true;
        Q.push(P(G[n][i], dis + 1));
      }
    }
  }
  for(int i=1;i<=n;i++)cout << i << ' ' << d[i] << endl;
}

C++: #include<bits/stdc++.h>

using namespace std;

#define rep(a, b) for(int i = a; i <= b; i++)
#define mst(a) memset(a, 0, sizeof(a))
#define mem(a, p) memset(a, p, sizeof(a))

const int MAX = 1e2 + 10;


bool mtx[MAX][MAX];
int vis[MAX];
int n;

queue<int> q;

void init(void)
{
	while(!q.empty())
		q.pop();
	mem(vis, -1);
	return;
}

bool check(int x, int y)
{
	if(mtx[x][y] && vis[y] == -1)
		return true;
	return false;
}

void Bfs(void)
{
	int cnt = 1;
	q.push(1);
	vis[1] = 0;
	while(!q.empty())
	{
		int cur = q.front();
		q.pop();
		rep(1, n)
		{
			if(check(cur, i))
			{
				q.push(i);
				vis[i] = vis[cur] + 1;
				cnt++;
				if(cnt == n)
					return;
			}
		}
	}
	return;
}

int main()
{
	while(~scanf("%d", &n))
	{
		init();
		rep(1, n)
		{
			int row;
			scanf("%d", &row);
			int num;
			scanf("%d", &num);
			while(num--)
			{
				int tmp;
				scanf("%d", &tmp);
				mtx[row][tmp] = true;
			}
		}
		
		Bfs();
		
		rep(1, n)
			printf("%d %d\n", i, vis[i]);
	}
	return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;

#define MAX 100
int INFTY = (1<<21);
int num,M[MAX][MAX];
int d[MAX];

void bfs(int s){
  queue<int> q;
  q.push(s);
  int u,i,v;
  for( i = 0; i < num; i++){
    //d[i] = INFINITY;
    d[i] = INFTY;
  }
  d[s] = 0;
  while( !q.empty()){
    u = q.front();
    q.pop();
  for(v = 0; v < num; v++){
    if( M[u][v] == 0){
      continue;
    }
    //if( d[v] != INFINITY){
    if( d[v] != INFTY){
      continue;
    }
    d[v] = d[u]+1;
    q.push(v);
  }
  }
  for(i = 0; i < num; i++){
    //cout << i+1 << " ";
    /*
    if(d[i] == INFINITY){
      cout << (-1);
    }
    else{
      cout << d[i] << endl;
    } 
    */
    cout << i+1 << " " << ( (d[i] == INFTY) ? (-1) : d[i] ) << endl;
  }
}

int main(){
  int u,k,v,i,j;
  cin >> num;
  for(i = 0; i < num; i++){
    for(j = 0; j < num; j++){
      M[i][j] = 0;
    }
  }

  for(i = 0; i < num; i++){
    cin >> u >> k;;
    u--;
    for(j = 0; j < k; j++){
      cin >> v;
      v--;
      M[u][v] = 1;
    }
  }
  bfs(0);
  return 0;
}