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 <stack>
#include <queue>

using namespace std;

#define MAX 100

#define WHITE 0
#define GRAY 1
#define BLACK 2

int T;
int N;

int M[MAX][MAX];
int C[MAX],D[MAX];

void bfs(int s)
{
    queue<int> *q = new queue<int>;

    q->push(s);
    D[s] = 0;
    C[s] = GRAY;

    while(!q->empty())
    {
        int u = q->front();
        q->pop();

        for (int v = 0; v < N; v++)
        {
            if (M[u][v] && C[v] == WHITE)
            {
                C[v] = GRAY;
                D[v] = D[u] + 1;
                q->push(v);
            }
        }

        C[u] = BLACK;
    }
}

int main ()
{
    cin >> N;

    for (int i = 0; i < N; i++)
    {
        C[i] = WHITE;
        D[i] = -1;

        for (int j = 0; j < N; j++)
        {
            M[i][j] = 0;
        }
    }

    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--;
            M[u][v] = 1;
        }
    }

/*
    for (int i = 0; i < N; i++)
    {
        for (int j = 0; j < N; j++)
        {
            if (j > 0)
                cout << " ";
            cout << M[i][j];
        }
        cout << endl;
    }
*/
    bfs(0);

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

    return 0;
}

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


int main() {
	int k[110][110];
int n,l,a,b;
cin>>n;
for(int j=0;j<n;j++){
	cin>>l>>a;
	for(int i=0;i<a;i++){
		cin>>b;
		k[j][b-1]=1;
	}
}
int q[105];
for(int j=0;j<n;j++){
	q[j]=-1;
	if(k[0][j]==1){
		q[j]=1;
	}
}
q[0]=0;
int u=1;
int m=1;
while(m<=n){

	for(int d=0;d<n;d++){
		if(q[d]==m){
			for(int h=0;h<n;h++){
				if(k[d][h]==1 &&q[h]==-1){
					q[h]=m+1;
				}
			}
		}
	}
m=m+1;	
}
for(int y=0;y<n;y++){
	cout<<y+1<<" "<<q[y]<<endl;
}

	return 0;
}

C++: #include<iostream>
#include<string>
#include<cstdio>
#include<algorithm>
#include<queue>
using namespace std;


int n;

string *color = new string[n];

int *d = new int[n];

queue<int> q;

int c[100][100];

void bfs(){
  color[0] = "gray";
  d[0] = 0;

  q.push(0);


  while(q.size() != 0){
    int u = q.front();
    q.pop();

    for(int v = 0; v < n; v++){
      if(c[u][v] == 1 && color[v] == "white"){
        color[v] = "gray";
        d[v] = d[u] + 1;
        q.push(v);
      }

    }
    color[u] = "black";
  }
}

int main(){

  cin >> n;

  color = new string[n];

  d = new int[n];


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

  for(int i = 0; i < n; i++){
    int x;
    cin >> x;
    int k;
    cin >> k;
    for(int j = 0; j < k; j++){
      int v;
      cin >> v;
      c[i][v - 1] = 1;
    }
  }

  for(int i = 0; i < n; i++){
    color[i] = "white";
  }

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

  bfs();





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




  return 0;
}

C++: #include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>

#include <iostream>
#include <complex>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>

#include <functional>
#include <cassert>

typedef long long ll;
using namespace std;

#define debug(x) cerr << __LINE__ << " : " << #x << " = " << (x) << endl;

#define mod 1000000007 //1e9+7(prime number)
#define INF 1000000000 //1e9
#define LLINF 2000000000000000000LL //2e18
#define SIZE 100010


int main(){
  int n;
  bool connected[200][200] = {};
  
  scanf("%d", &n);

  for(int i=0;i<n;i++){
    int u, k, v;

    scanf("%d%d", &u, &k);
    u--;
    
    for(int j=0;j<k;j++){
      scanf("%d", &v);
      v--;

      connected[u][v] = true;
    }
  }

  queue<int> q1, q2;
  bool visited[200] = {};
  int ans[200];

  for(int i=0;i<n;i++) ans[i] = -1;
  
  q1.push(0);

  for(int i=0;q1.size();i++){

    while(q1.size()){
      int p = q1.front();
      q1.pop();

      if(visited[p]) continue;
      visited[p] = true;

      ans[p] = i;
      
      for(int j=0;j<n;j++){
        if(connected[p][j]){
          q2.push(j);
        }
      }
    }

    q1 = q2;
  }

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

C++: #include<iostream>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#include<list>
#include<string>
#include<cstring>
#include<cstdlib>
#include<cstdio>
#include<cmath>
using namespace std;

const int NIL = -1;
const int MAX = 20001;

int G[101][101];
int color[101], d[101];
int t = 0;

int main(void)
{
	int n, k, v, u;
	queue<int>Q;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> u >> k;
		for (int i = 0; i < k; i++) {
			cin >> v;
			G[u][v] = 1;
		}
	}
	for (int i = 1; i <= n; i++)
		d[i] = MAX;
	color[1] = 1;
	d[1] = 0;
	Q.push(1);
	while (Q.size()) {
		u = Q.front();
		Q.pop();
		for (int v = 1; v <= n; v++) {
			if (G[u][v] && color[v] == 0) {
				color[v] = 1;
				d[v] = d[u] + 1;
				Q.push(v);
			}
		}
		color[u] = 2;
	}
	for (int i = 1; i <= n; i++) {
		if (d[i] == MAX)
			d[i] = -1;
	}
	for (int i = 1; i <= n; i++) {
		cout << i << " " << d[i] << endl;
	}
	return 0;
}