Go: package main

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

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Scan()
	num, _ := strconv.Atoi(sc.Text())
	nodes := make(map[int]*node)

	for i := 0; i < num; i++ {
		sc.Scan()
		id, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		nodeNum, _ := strconv.Atoi(sc.Text())
		n := node{id, make([]int, 0), -1}
		for j := 0; j < nodeNum; j++ {
			sc.Scan()
			nid, _ := strconv.Atoi(sc.Text())
			n.nexts = append(n.nexts, nid)
		}
		nodes[id] = &n
	}
	nodes[1].depth = 0

	walk(1, 0, &nodes)
	for i := 1; i < len(nodes)+1; i++ {
		fmt.Printf("%v %v\n", (*nodes[i]).id, (*nodes[i]).depth)
	}
}

var time int
var record [100][100]bool
var q Queue

func walk(nid int, from int, nodes *map[int]*node) {
	q.Enqueue((*nodes)[nid])
	for !q.IsEmpty() {
		n := q.Dequeue().(*node)
		for _, v := range n.nexts {
			n2 := (*nodes)[v]
			if n2.depth != -1 {
				continue
			}
			n2.depth = n.depth + 1
			q.Enqueue((*nodes)[v])
		}
	}
}

type node struct {
	id    int
	nexts []int
	depth int
}

// Queue is Queue
type Queue struct {
	val []interface{}
}

// Enqueue value
func (queue *Queue) Enqueue(val interface{}) {
	queue.val = append(queue.val, val)
}

// Dequeue value
func (queue *Queue) Dequeue() interface{} {
	res := queue.val[0]
	queue.val = queue.val[1:len(queue.val)]
	return res
}

// IsEmpty return true when queue is empty
func (queue *Queue) IsEmpty() bool {
	return len(queue.val) == 0
}

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)
{
	if (g->k >= 0) {
		for (auto i = g->node.begin(); i != g->node.end(); ++i) {
			if (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 n, u, xk, v;
	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 <vector>
#include <algorithm>
#include <deque>
using namespace std;
 
struct status{
    int idx_node;
    vector<int> children;
    int visited = 0;
    int depth = -1;
};
 
deque<int> schedule; 
vector<status> graph;

int depth = 1;
void bfs(){
    if (schedule.size()>1){
        
        int now_node = schedule.front();
        schedule.pop_front();
        
        switch(now_node){
            case 0: {
                ++depth;
                schedule.push_back(0);
                break;
            }
            default: {
                for(auto& next_node:graph[now_node-1].children){
                    if(graph[next_node-1].visited) continue;
                    
                    graph[next_node-1].visited = 1;
                    graph[next_node-1].depth = depth;  
                    schedule.push_back(next_node);
                }
            }
        }
        bfs();
    }
}
 

int main(void){cin.tie(0);ios::sync_with_stdio(false);
 
    //stdi
    int nb_nodes; cin >> nb_nodes;
    graph.resize(nb_nodes);
    for(auto& times:graph){
        int idx_node; cin >> idx_node; graph[idx_node-1].idx_node = idx_node;
        int nb_edges; cin >> nb_edges; graph[idx_node-1].children.resize(nb_edges);
        for(auto& a:graph[idx_node-1].children){
            cin >> a;
        }
        sort(graph[idx_node-1].children.begin(),graph[idx_node-1].children.end());
    }
    
    //bfs
    graph[1-1].depth = 0;
    schedule.push_back(1);
    schedule.push_back(0);
    bfs();
     
    //stdo
    for(auto& a:graph){
        cout<<a.idx_node<<" "
            <<a.depth<<"\n";
    }
}

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;
  vector<int> G[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--;
      G[u].push_back(v);
    }
  }
 
  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<G[p].size();j++){
        q2.push(G[p][j]);
      }
    }
 
    q1 = q2;
    q2 = queue<int>();
  }
 
  for(int i=0;i<n;i++)
    printf("%d %d\n", i+1, ans[i]);
   
  return 0;
}

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

int main(){
  queue<int> q;
  int n,k,u,max=0;
  int g[101]={},f[101];
  int d[101][101]={};
  int di;
  cin>>n;
  for(int i=0;i<101;i++) f[i]=-1;
  f[1]=0;
  g[1]=1;
  for(int i=0;i<n;i++){
    cin>>u>>k;
    if(max<k) max=k;
    for(int j=0;j<k;j++){
      cin>>di;
	d[u][j]=di;
    }
  }

  q.push(1);

  int a,c[101]={};
  while(!q.empty()){
 a=q.front();
    for(int i=0;i<=max;i++){

      if( d[a][i]>1 && g[d[a][i]]==0){
	g[d[a][i]]=1;
	q.push(d[a][i]);
	 c[d[a][i]]=c[a]+1;
      }
    }
      q.pop();
  }
  for(int i=1;i<=n;i++) cout<<i<<" "<<c[i]<<endl;
  return 0;
}

C++: #include <iostream>
#include <queue>
using namespace std;
queue<int> qu;
int v[101][101];
int dis[101], n;
int d = 0;
int tf;
inline void b1(int t) {
	for (int i = 1; i <= n; i++) {
		if (v[t][i]) {
			tf = 1;
			qu.push(i);
			dis[i] = d + 1;
			for (int j = 1; j <= n; j++)
				v[j][i] = 0;
		}
	}
}
inline void b2() {
	tf = 0;
	for (int i = 1; i <= n; i++)
		if (dis[i] == d) {
			b1(i);
			qu.pop();
		}
	d++;
}
inline void bfs() {
	tf = 1;
	b1(1);
	d++;
	qu.pop();
	while (tf) {
		b2();
	}
}
int main() {
	int u, k, s;
	cin >> n;
	for (int i = 2; i <= n; i++) {
		dis[i] = -1;
	}
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= n; j++) {
			v[i][j] = 0;
		}
	}
	for (int i = 0; i < n; i++) {
		cin >> u;
		cin >> k;
		for (int j = 0; j < k; j++) {
			cin >> s;
			v[u][s] = 1;
		}
	}
	qu.push(1);
	for (int i = 1; i <= n; i++)
		v[i][1] = 0;
	bfs();
	for (int i = 1; i <= n; i++) {
		cout << i << " " << dis[i] << endl;
	}
	return 0;
}