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 <bits/stdc++.h>
using namespace std;

#define MAX 105
#define INFTY 10000000

int n, M[MAX][MAX];
int d[MAX];

void bfs(int s){
    //最短距離を初期化
    for(int u=1; u<=n; u++){
        d[u] = INFTY;
    }
    queue<int> Q;
    d[s] = 0;
    Q.push(s);

    while(!(Q.empty())){
        int v = Q.front();
        for(int u=1; u<=n; u++){
            if(M[v][u] == 1  &&  d[u] == INFTY){
                d[u] = d[v]+1;
                Q.push(u);
            }
        }
        Q.pop();
    }

    //出力
    for(int u=1; u<=n; u++){
        if(d[u] == INFTY) printf("%d -1\n", u);
        else printf("%d %d\n", u, d[u]);
    }
}

//グラフの幅優先探索(stackを用いる)
int main(){
    cin >> n;
    //隣接リスト表現→隣接行列表現への変換
    for(int i=1; i<=n; i++){
        for(int j=1; j<=n; j++){
            M[i][j] = 0;
        }
    }
    for(int i=1; i<=n; i++){
        int u, k;
        cin >> u >> k;
        for(int j=1; j<=k; j++){
            int v;
            cin >> v;
            M[u][v] = 1;
        }
    }

    bfs(1);

    return 0;
}

C++: #include<iostream>
#include<queue>
#define rep(i, n) for (int i=0; i<(n); i++)
using namespace std;

static const int N=100;
static const int INF=(1<<12);

int n;
bool M[N][N];
int d[N]; //距離で状態を管理するためcolor不要

void bfs(int s) {
  queue<int> que;
  que.push(s);
  rep(i, n) d[i]=INF;
  d[s]=0;

  while (!que.empty()) {
    int u=que.front();
    que.pop();
    rep(v, n) {
      if (!M[u][v]) continue;
      if (d[v]!=INF) continue;
      d[v]=d[u]+1;
      que.push(v);
    }
  }
}

int main() {
  cin>>n;
  rep(i, n) {
    rep(j, n) {
      M[i][j]=false;
    }
  }
  rep(i, n) {
    int u,k; cin>>u>>k;
    u--;
    rep(i, k) {
      int v; cin>>v;
      v--;
      M[u][v]=true;
    }
  }

  bfs(0);
  rep(i, n) {
      if (d[i]==INF) cout<<i+1<<" "<<-1<<endl;
      else cout<<i+1<<" "<<d[i]<<endl;
  }
  return 0;
}

C++: #include <bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
#define SIZE 200005
#define INF 1000000005LL
//#define INF 1e18
#define MOD 1000000007

using namespace std;
typedef long long int ll;
typedef pair <int,int> P;

int n;

vector<int> E[SIZE];
int d[SIZE];

void bfs(int s){
  queue<int> que;
  que.push(s);
  fill(d,d+SIZE,INF);
  d[s] = 0; 
  while(!que.empty()){
    int v = que.front();que.pop();
    for(int to : E[v]) if(d[to] == INF){
      d[to] = d[v]+1;
      que.push(to);
    }
  }
}

int main(){
  cin >> n;
  rep(i,0,n){
    int u,k;
    cin >> u >> k;
    rep(i,0,k){
      int v;
      cin >> v;
      E[u].push_back(v);
    }
  }
  bfs(1);
  rep(i,1,n+1){
    cout << i << " ";
    if(d[i] == INF)cout << -1 << endl;
    else cout << d[i] << endl;
  }

  return 0;
}

C++: // 幅優先探索
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<stack>
#include<algorithm>
#include<iostream>
#include<cmath>
#include<vector>

#include<queue>

using namespace std;

#define MAX_N 100
// 値の定義
const int INV = -1;
const int EXIST = 1;
const int NO_EXIST = 0;

const int YES = 0;
const int NO = -1;

// グラフ情報を保持する配列
int ary_graph[MAX_N + 1][MAX_N + 1];

// 頂点１からの距離を保持する配列
int vertex_distance[MAX_N + 1];
// 頂点１からの訪問状態を保持する配列
int ary_visit[MAX_N + 1];

int n = 0;
int nt[MAX_N + 1];

void widthFirstSearch(int start_vertex);

int main(void)
{
    int u, num, v_num;

    for(int i = 0; i < MAX_N + 1; i++)
    {
    	vertex_distance[i] = 0;
        ary_visit[i] = NO;

        for(int j = 0; j < MAX_N + 1; j++)
        {
            // 配列の初期化
            ary_graph[i][j] = NO_EXIST;
        }
    }

    cin >> n;

    for(int i = 0; i < n; i++)
    {
        cin >> u >> num;

        // 0オリジンにする
        u--;

        for(int j = 0; j < num; j++)
        {
            // 隣接点を記憶する
            cin >> v_num;

            // 0オリジンにする
            v_num--;
            ary_graph[u][v_num] = EXIST;
        }
    }

    // 頂点１から幅優先探索を実施
    widthFirstSearch(0);

    // 結果の表示
    for(int i = 0; i < n; i++)
    {
        if( i != 0 && vertex_distance[i] == 0 )
        {
            // 開始点から到達不可能な点は, 距離に-1を設定
            // ただし, 開始点自身は除く
            vertex_distance[i] = INV;
        }

        printf("%d %d\n", i + 1, vertex_distance[i]);
    }

    return 0;
}

// u に隣接する v を番号順に取得
int next(int u)
{
    int ret = INV;

    for(int v = nt[u]; v < n; v++)
    {
        nt[u] = v + 1;

        if( ary_graph[u][v] == EXIST )
        {
            // 隣接点が存在する
            ret = v;
            break;
        }
    }

    return ret;
}

// 幅優先探索を実施する関数
// start_vertex : 起点となる頂点のNo.
// vertex_num : グラフの頂点数
void widthFirstSearch(int start_vertex)
{

    queue<int> Q;

    Q.push(start_vertex);
    vertex_distance[start_vertex] = 0;
    ary_visit[start_vertex] = YES;

    while( !Q.empty() )
    {
        int u = Q.front();

        for(int i = 0; i < n; i++)
        {
            // 隣接点を全て検索する
            int v = next(u);

            if( v == INV )
            {
                // 隣接点が無くなったらキューから削除して, 処理終了
                Q.pop();
                break;
            }

            if( ary_visit[v] == NO
                && ary_graph[u][v] == EXIST )
            {
                // 訪問済み
                ary_visit[v] = YES;

                Q.push(v);
                vertex_distance[v] = vertex_distance[u] + 1;
            }
        }
    }

    return;
}