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 <vector>
#include <queue>

using namespace std;

void bfs(int v,vector<vector<int>>& vertex, int d[]);

//int depth = 0;

int main(){
    int n;
    cin >> n;
    int num;
    int tmp2;
    int d[n];
    for(int i=0;i<n;i++){
        d[i] = -1;
    }
    vector<vector<int>> vertex;
    vector<int> tmp;
    for(int i=0;i<n;i++){
        cin >> num;
        cin >> num;
        for(int j=0;j<num;j++){
            cin >> tmp2;
            tmp.push_back(tmp2-1);
        }
        vertex.push_back(tmp);
        tmp.clear();
    }
    bfs(0, vertex, d);
    
    for(int i=0;i<n;i++){
        cout << i+1 << " " <<  d[i] << endl;
    }
    return 0;
}

void bfs(int v, vector<vector<int>>& vertex, int d[]){
    queue<int> Q;
    Q.push(v);
    d[v] = 0;
    while(!Q.empty()){
        v = Q.front();
        Q.pop();
        bool flag = false;
        for(int i : vertex[v]){
            if(d[i]==-1){
                d[i] = d[v] + 1;
                Q.push(i);
                flag = true;
            }
        }
    }
}

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

typedef long long ll;
typedef pair<ll, ll> P;

#define pb push_back
#define rep(i, n) for(int i = 0; i < (n); i++)
#define FOR(i, a, n) for(int i = a; i < (n); i++)
#define mod (ll)(1e9+7)
#define int ll

static const int N = 100;
static const int no = -1;

__attribute__((constructor))
void initial() {
  cin.tie(0);
  ios::sync_with_stdio(false);
}

ll graph[N][N] = {{}}, d[N] = {}, n;

void bfs(int v) {
  queue<int> q;
  q.push(v);
  ll u;
  for(int i = 1; i <= n; i++) d[i] = no;
  d[v] = 0;
  while(!q.empty()) {
    u = q.front(); q.pop();
    for(int i = 1; i <= n; i++) {
      if(graph[u][i] == 0 continue;
      if(d[i] != no) continue;
      d[i] = d[u] + 1;
      q.push(i);
    }
  }
}

signed main() {
	ll u, v, k;
  cin >> n;
  rep(i, n) {
    cin >> u >> k;
    rep(j, k) {
      cin >> v;
      graph[u][v] = 1;
    }
  }

  bfs(1);

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

	return 0;
}

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

struct{
	int link;
	int stg;
}typedef LinkStage;

class Vertex{
	private:
		int* links;
		int index;
		int num;
		bool arrived;
		int id;
		int d;
	public:
		Vertex(int u,int k):id(u), num(k),links(new int[k]),index(0),arrived(false),d(-1){}
		void addLink(int);
		void enQueueLinks(queue<LinkStage>*,int);	
		void print();
};

void Vertex::addLink(int link){
	links[index] = link - 1;
	index++;
}

void Vertex::enQueueLinks(queue<LinkStage>* taskQueue,int dist){
	if(arrived)
		return;

	for(int i = 0; i < index;i++){
		LinkStage stage;
		stage.link = links[i];
		stage.stg = dist + 1;
		taskQueue->push(stage);
	}
	arrived = true;
	d = dist;
}

void Vertex::print(){
	cout << id << " " << d << endl;
}

int main(){
	int n;
	cin >> n;
	Vertex** vertexes = new Vertex*[n];
	for(int i = 0;i < n;i++){
		int u;
		cin >> u;
		int k;
		cin >> k;
		Vertex* vertex = new Vertex(u,k);
		for(int j = 0;j < k;j++){
			int v;
			cin >> v;
			vertex->addLink(v);
		}
		vertexes[u - 1] = vertex;
	}
	queue<LinkStage> task;
	vertexes[0]->enQueueLinks(&task,0);
	while(!task.empty()){
		LinkStage curr = task.front();
		task.pop();
		int nextI = curr.link;
		int d = curr.stg;
		vertexes[nextI]->enQueueLinks(&task,d);
	}
	for(int i = 0; i < n;i++){
		vertexes[i]->print();
	
	}
	
	return 0;
}

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

int n;
vector<vector<int> > G;
vector<int> D;

void bfs(int src){
    queue<int> Q;
    Q.push(src);
    D[src] = 0; // ?????????
    while(!Q.empty()){
        int cur = Q.front(); // ??????????´???????????????????
        Q.pop();
        for(int dst = 0; dst < n; ++dst){ // ???????????? dst ????????????
            if(G[cur][dst] == 1 && D[dst] == -1){ // cur??????dst???????????????,dst???????¨??????????
                D[dst] = D[cur] + 1;
                Q.push(dst); // dst????¨??????????????????????
            }
        }
    }
}

int main(){
    cin >> n;
    G = vector<vector<int> >(n, vector<int>(n, 0));
    D = vector<int>(n, -1);
    for(int i=0; i<n; ++i){
        int u;
        cin >> u;
        // 1~n???index?????¨????????????????????????????????????1????????????0~n-1????????????
        u -= 1;
        int k;
        cin >> k;
        for(int j=0; j<k; ++j){
            int v;
            cin >> v;
            v -= 1;
            G[u][v] = 1;
        }
    }
    bfs(0);
    for(int i=0; i<n; ++i){
        cout << i+1 << " " << D[i] << endl;
    }
}