Go: package main

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

type vertexId int

type vertex struct {
	id vertexId
	visitedAt int
	adjs []vertexId
}

func createVertex(id int, adjsInt []int) vertex {
	adjs := make([]vertexId, len(adjsInt))
	for i := 0; i < len(adjs); i++ {
		adjs[i] = vertexId(adjsInt[i])
	}
	return vertex{
		id: vertexId(id),
		visitedAt: -1,
		adjs: adjs,
	}
}

func (v *vertex) isVisited() bool {
	return v.visitedAt >= 0
}

func bfs(id vertexId, vqueue []vertexId, vertices []vertex) {
	vertex := &vertices[id-1]
	for _, vid := range vertex.adjs {
		if !vertices[vid-1].isVisited() {
			(&vertices[vid-1]).visitedAt = vertex.visitedAt+1
			vqueue = append(vqueue, vid)
		}
	}
	if len(vqueue) > 0 {
		nextId := vqueue[0]
		nextVqueue := vqueue[1:]
		bfs(nextId, nextVqueue, vertices)
	}
}

func solveBfs(vertices []vertex) {
	vertex := &vertices[0]
	vertex.visitedAt = 0
	vqueue := make([]vertexId, 0)
	bfs(vertex.id, vqueue, vertices)
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	vertices := make([]vertex, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjN, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjs := make([]int, adjN)
		for j := 0; j < adjN; j++ {
			adjId, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjs[j] = adjId
		}
		vertices[i] = createVertex(id, adjs)
	}

	solveBfs(vertices)

	for i := 0; i < n; i++ {
		fmt.Printf("%d %d\n", vertices[i].id, vertices[i].visitedAt)
	}
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

func nextInt(sc *bufio.Scanner) (int, error) {
	return strconv.Atoi(nextText(sc))
}

C++: #define scanf_s scanf
#include <string>
#include <stdio.h>
#include <math.h>
#include <stack>
#include <queue>
#include <list>
#include <vector>
#include <iostream>
using namespace std;

#define MAX 100
//#define MAX_ 1000
struct Graph
{
	int id, k;
	list<int> node;
	int d = -1;
};
Graph G[MAX];
//int cou = 0;
void Breadth_cou(Graph *g,int cou)
{
	for (auto i = g->node.begin(); i != g->node.end(); ++i) {
		if (G[*i].d == -1 || G[*i].d > cou) {
			if (G[*i].d > cou)
				Breadth_cou(&G[*i], G[*i].d + 1);
			G[*i].d = cou;
			
		}
	}
	g->k = 0;
}
void Breadth(Graph *g)
{
	if (g->k > 0) {
		Breadth_cou(g, g->d + 1);
		for (auto i = g->node.begin(); i != g->node.end(); ++i) {
			Breadth(&G[*i]);
		}
	}
}
int main(void)
{
	int u, xk, v, n;
	scanf_s("%d", &n);
	for (int i = 0; i < n; ++i) {
		scanf_s("%d %d", &u, &xk);
		G[u - 1].id = u - 1;
		G[u - 1].k = xk;
		for (int j = 0; j < xk; ++j) {
			scanf_s("%d", &v);
			G[u - 1].node.push_back(v - 1);
		}
	}
	G[0].d = 0;
	Breadth(&G[0]);
	for (int i = 0; i < n; ++i) {
		printf("%d %d\n", G[i].id + 1, G[i].d);
	}
}

C++: #include<iostream>
#include<cstdio>
#define INF 1<<30
#define MAX 100000
using namespace std;

class Queue{
private:
  int inf[MAX];
  int head,tail;
 
public:
 
  Queue(){
    syokika();
  }
 
  void syokika(){
    head = 0;
    tail = 0;
  }
 
  void push(int x){
    inf[tail]=x;
    if(MAX == tail+1)tail = 0;
    else tail++;
  }
 
  void pop(){
    if(MAX == head+1)head=0;
    else head++;
  }
 
  int front(){
    return inf[head];
  }
 
  bool empty(){
    if(tail - head == 0)return true;
    else return false;
  }
 
  int size(){
    return tail - head;
  }
 
};

int imap[200][200];
int k[200] = {0}; 
int ans[200] = {0};
bool used[200];

int main(){
  int n,u[1000];
  cin >> n;
  for(int i=0;i<200;i++)for(int j=0;j<200;j++)imap[j][i] = INF;  
  for(int i=0;i<n;i++){
    cin >> u[i];
    cin >> k[u[i]];
    for(int j=0;j<k[u[i]];j++){
      cin >> imap[u[i]][j];
    }
  }

   int h;
  for(int i=0;i<n;i++){
    int Min = i;
    for(int j=i;j<n;j++){
      if(u[Min] > u[j])Min = j; 
    }
    h = u[Min];
    u[Min] = u[i];
    u[i] = h;
  }

  /*
  for(int i=0;i<n;i++){
    for(int j=0;j<k[u[i]];j++){
      cout << imap[u[i]][j] << " ";
    }
    cout << endl;
  }
  */

  Queue que = Queue();

  que.push(u[0]);

  while(!que.empty()){
    int p = que.front(); que.pop();
    for(int i=0;i<k[p];i++){
      if(!used[imap[p][i]]){
	que.push(imap[p][i]);//cout << "push!= " << imap[p][i] << endl;
	used[imap[p][i]] = true;
	ans[imap[p][i]] = ans[p] + 1;
      }
    }
  }
  for(int i=0;i<n;i++)cout << u[i] << endl;

 
  

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

  return 0;
}

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

int main() {
    int n;
    cin >> n;
    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<bool> visited(n, false);
    vector<int> d(n, -1);
    queue<int> que;
    que.push(0);
    visited[0] = true;
    d[0] = 0;

    while (!que.empty()) {
        int u = que.front(); que.pop();
        for (int i = 0; i < G[u].size(); i++) {
            int v = G[u][i];
            if (!visited[v]) {
                que.push(v);
                visited[v] = true;
                d[v] = d[u] + 1;
            }
        }
    }

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

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

using namespace std;
static const int N = 100;
static const int INFTY = (1 << 21);

int n, M[N][N];
intd  d[N];

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

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

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

#define N 101

void BreadthFirstSearch();

class queue{
public:
    int array[100];
    int head = -1;
    int tail = -1;
    
    void push(int v) {
        tail = (tail + 1) % N;
        array[tail] = v;
        return;
    }
    
    int pop() {
        head = (head + 1) % N;
        return array[head];
    }
    
    int show() {
        return array[head];
    }
    
    bool empty() {
        if(head == tail) return true;
        else return false;
    }
};

int n;
int d;
int a[N][N];
queue q;
int list[N];

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    cin>>n;
    int u, k, v;
    for(int i = 0; i < n; i++) {
        cin>>u>>k;
        
        int c = 0;
        for(int j = 0; j < k; j++) {
            cin>>v;
            a[u][c] = v;
            c++;
        }
    }
    
    for(int i = 1; i <= n; i++) list[i] = -1;
    
    q.push(1);
    list[1] = 0;
    while(!q.empty()) {
        d++;
        BreadthFirstSearch();
    }
    
    for(int i = 1; i <= n; i++) {
        cout<<i<<' '<<list[i]<<endl;
    }
    
    return 0;
}

void BreadthFirstSearch() {
    int u = q.pop();
    int i = 0;
    
    while(a[u][i] != 0) {
        if(list[ a[u][i] ] != -1) {
            i++;
            continue;
        }
        q.push(a[u][i]);
        list[ a[u][i] ] = list[u] + 1;
        i++;
    }
}