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<algorithm>
#include<queue>
using namespace std;

int n, d[110];
bool a[110][110] = {};

void bfs(int u){
  
  queue<int> Q;
  
  Q.push(u);
  d[u] = 0;
  
  while(Q.size()){
    int p = Q.front();
    Q.pop();
    
    for(int i = 2;i <= n;i++){
      if(a[p][i] && d[i] == 0){
        Q.push(i);
        d[i] = d[p] + 1;
      }
    }
  }
}

int main(){
  
  int u, k, v;
  
  cin >> n;
  for(int i = 0;i < n;i++){
    cin >> u >> k;
    for(int j = 0;j < k;j++){
      cin >> v;
      a[u][v] = true;
    }
  }
  
  bfs(1);
  
  for(int i = 1;i <= n;i++){
    if(d[i] || i == 1) cout << i << " " << d[i] << endl;
    else cout << i << " " << -1 << endl;
  }
  
  return 0;
}

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

using namespace std;

const int N = 100;
const int Inf = 1e9;

int m[N][N];
int d[N];
int n;

void bfs(int);

int main(int argc, char const *argv[]) {
  cin >> n;
  for (int i = 0; i < N; ++i) {
    for (int j = 0; j < N; ++j) {
      m[i][j] = 0;
    }
    d[i] = -1;
  }

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

  return 0;
}

void bfs(int s) {
  queue<int> q;
  q.push(s);
  d[s] = 0;
  while (!q.empty()) {
    int u = q.front();
    q.pop();
    for (int i = 0; i < n; ++i) {
      if (m[u][i] == 0 || d[i] != -1) {
        continue;
      }
      d[i] = d[u] + 1;
      q.push(i);
    }
  }
  for (int i = 0; i < n; ++i) {
    cout << i + 1 << " " << d[i] << '\n';
  }
}

C++: //By Vlgd
#include<bits/stdc++.h>
using namespace std;
int G[101][101],n,dis[101],vis[101]={0},cur=0;
queue<int>q;
void bfs(int u){
	q.push(u);
	vis[u]=1;
	dis[u]=0;
	while(!q.empty()){
		int w=q.front();q.pop();
		for (int v=1;v<=n;v++) 
			if (G[w][v]&&!vis[v]){ 
				dis[v]=dis[w]+1;
				q.push(v);
				vis[v]=1;
			}
	}
}
main(){
	int u,v,deg;
	scanf("%d",&n);
	for (int i=1;i<=n;i++) dis[i]=-1;
	for (int i=0;i<n;i++){
		scanf("%d%d",&u,&deg);
		for (int j=0;j<deg;j++){
			scanf("%d",&v);
			G[u][v]=1;
		}
	}
	bfs(1);
	for (int i=1;i<=n;i++) printf("%d %d\n",i,dis[i]);
}

C++: #include<iostream>
#include<queue>
#include<algorithm>
#include<cstring>
using namespace std;
#define MAX 100+5
int num;
int m[MAX][MAX],a[MAX],d[MAX],color[MAX];//color[i]中0--白色；1--灰色；2--黑色； 
void bfs(int v){
	queue<int> q;
	q.push(v);d[v]=0;
	color[v]=1;
	int shou;
	while(!q.empty()){
	shou=q.front();q.pop();
	for(int i=1;i<=num;i++){
		if(m[shou][i]==1&&color[i]==0){
			q.push(i);d[i]=d[shou]+1;color[i]=1;
		}
		color[shou]=2;
	}
	}
	return ;
}
int main(){
	memset(m,0,sizeof(m));
	memset(color,0,sizeof(color));
	memset(d,-1,sizeof(d)); 
	cin>>num;
	for(int i=1;i<=num;i++){
		int cnt;
		cin>>a[i]>>cnt;
		for(int j=0;j<cnt;j++){
			int c;
			cin>>c;
			m[a[i]][c]=1; 
		}
	}
	bfs(1);
	for(int i=1;i<=num;i++){
		cout<<a[i]<<" "<<d[a[i]]<<endl;
	}
	
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <stack>
#include <queue>
#include <cmath>
#include <string>
using namespace std;
typedef vector<int> vint;
typedef vector<long long> vll;
typedef pair<int,int> pint;
typedef long long ll;
#define range(i,a,b) for(int i=a;i<b;++i)
#define rep(i,n) range(i,0,n)
#define INF 10000000000 //10^10
#define PI 3.141592
#define pb push_back

int main(){
    //内部処理は0indexで行う

    //入力
    int n;
    cin >> n;
    vector<vint> adj(n);
    rep(i,n){
        int u,k;
        cin >> u >> k;
        rep(j,k){
            int v;
            cin >> v;
            adj[u-1].pb(v-1);
        }
    }

    //計算
    vint d(n,-1);
    d[0]=0;
    queue<int> Q;
    Q.push(0);
    while(!Q.empty()){
        int cur=Q.front(); Q.pop();
        rep(i,adj[cur].size()){
            int dst=adj[cur][i];
            if(d[dst]==-1){
                d[dst]=d[cur]+1;
                Q.push(dst);
            }
        }
    }

    //出力
    rep(i,n){
        cout << i+1 << ' ' << d[i] << endl;
    }
}

C++: #define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
#define rep(i, n) for(ll i = 0; i < (n); ++i)
#define FOR(i, m, n) for(ll i = m; i < (n); i++)
#define all(x) (x).begin(),(x).end()
using namespace std;
typedef long long ll;
using vi = vector<int>;
using vii = vector<vi>;
using pii = pair<int, int>; 
using vl = vector<ll>;
using vll = vector<vl>;
using pll = pair<ll, ll>;

int main() {
    ll n;
    cin >> n;
    vll G(n);
    rep(i, n){
        ll u, k;
        cin >> u >> k;
        u--;
        rep(j, k){
            ll a;
            cin >> a;
            a--;
            if(a < 0) continue;
            G[u].push_back(a);
        }
    }
    
    vl dist(n, -1);
    queue<ll> que;
    dist[0] = 0;
    que.push(0);
    while(!que.empty()){
        ll v = que.front();
        que.pop();

        for(auto nv : G[v]){
            if(dist[nv] != -1) continue;
            dist[nv] = dist[v] + 1;
            que.push(nv);
        }
    }

    rep(i, n){
        cout  << i+1 << " " <<  dist[i] << endl;
    }
}