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<cmath>
#include<algorithm>
#include<string>
#include<vector>
#include<stack>
#include<queue>
#include<set>
#include<map>
#include<iomanip>
#include<bitset>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> P;
typedef pair<ll,P> P1;
typedef pair<P,P> P2;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-7
#define INF 1000000000
#define fi first
#define sc second
#define rep(i,x) for(ll i=0;i<x;i++)
#define repn(i,x) for(ll i=1;i<=x;i++)
#define SORT(x) sort(x.begin(),x.end())
#define ERASE(x) x.erase(unique(x.begin(),x.end()),x.end())
#define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin())
#define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin())

const int MAX = 510000;
const int MOD = 1000000007;

using Graph = vector<vector<int> >;

int main() {
    // 頂点数と辺数
    int N; cin >> N;

    // グラフ入力受取 (ここでは無向グラフを想定)
    Graph G(N);
    for (int i = 0; i < N; ++i) {
        int g, k; cin >> g >> k;
        rep(j,k){
          int a;
          cin >> a;
          a--;
          G[i].push_back(a);
        }
    }

    // BFS のためのデータ構造
    vector<int> dist(N, -1); // 全頂点を「未訪問」に初期化
    queue<int> que;

    // 初期条件 (頂点 0 を初期ノードとする)
    dist[0] = 0;
    que.push(0); // 0 を橙色頂点にする

    // BFS 開始 (キューが空になるまで探索を行う)
    while (!que.empty()) {
        int v = que.front(); // キューから先頭頂点を取り出す
        que.pop();

        // v から辿れる頂点をすべて調べる
        for (int nv : G[v]) {
            if (dist[nv] != -1) continue; // すでに発見済みの頂点は探索しない

            // 新たな白色頂点 nv について距離情報を更新してキューに追加する
            dist[nv] = dist[v] + 1;
            que.push(nv);
        }
    }

    // 結果出力 (各頂点の頂点 0 からの距離を見る)
    for (int v = 0; v < N; ++v) cout << v + 1 << " " << dist[v] << endl;
}

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

int n, u, k, v;
int a[100][100] = {{0}};
int b[100] = { - 1 };
queue<int> q;

int main() {
	cin >> n;
	for ( int i = 0; i < n; i++ ) {
		cin >> u >> k;
		for ( int j = 0; j < k; j++ ) {
			cin >> v;
			a[u - 1][v - 1] = 1;
		}
	}
	b[0] = 0;
	q.push( 0 );
	while ( ! q.empty() ) {
		u = q.front();
		for ( int i = 0; i < n; i++ ) {
			if ( a[u][i] == 1 && b[i] == -1 ) {
				b[i] = b[u] + 1;
				q.push( i );
			}
		}
		q.pop();
	}
	for ( int i = 0; i < n; i++ )
		cout << ( i + 1 ) << " " << b[i] << endl;
}

C++: #include <iostream>
#include <string>
#include <stack>
#include <queue>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <algorithm>

#include <cstdio>

using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define repc(i, s, n) for (int i = (s); i <= (n); i++)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; i--)
#define rrepc(i, s, n) for (int i = (s); i >= (n); i--)
#define print_array(ary, size) cout << ary[0]; rep1(i, 1, size - 1) cout << ' ' << ary[i]; cout << endl;
typedef long long ll;
typedef unsigned long long ull;

int M[100][100] = { 0 };
int dist[100];

int main()
{
	int n, u, k, v;
	int current;
	int current_dist = 0;
	queue<int> Q;

	cin >> n;
	rep(i, n) {
		dist[i] = -1;
		cin >> u >> k;
		rep(j, k) {
			cin >> v;
			M[u - 1][v - 1] = 1;
		}
	}

	dist[0] = current_dist;
	Q.push(1);

	while (!Q.empty()) {
		current = Q.front();
		current_dist = dist[current - 1];

		rep(i, n) {
			if (M[current - 1][i] && dist[i] == -1) {
				Q.push(i + 1);
				dist[i] = current_dist + 1;
			}
		}
		Q.pop();
	}

	rep(i, n) cout << i + 1 << ' ' << dist[i] << endl;

	return 0;
}

C++: #include <stdio.h>
#include <string.h>
#include<iostream>
#include<queue>
using namespace std;

char s[13][1];
int D[102][102];
int A[103],f[103],w,h,n,sx,sy,gx,gy,e,g[103];
int   kensa(int ,int);
int main(){
	queue<int> P;
	int i,j,a,b,c,d;
	for(i=0;i<100;i++){
		for(j=0;j<100;j++){
			D[i][j]=-1;		
		}					
	}						
	for(i=0;i<100;i++){		
		A[i]=0;				
		f[i]=-1;
		g[i]=0;
	}							
	scanf("%d" ,&a);//     a=4
	for(i=1;i<=a;i++){
        scanf("%d",&b);		//
		scanf("%d",&b);			//b=2					//
		for(j=1;j<=b;j++){		//
		scanf("%d",&c);			//					//
		D[i][c]=1;
//
		}						//D[???][???]
	}				
	for(i=1;i<=a;i++){
		for(j=1;j<=a;j++){
	//		printf("%d %d %d\n",i,j,D[i][j]);
		}	
	}//
	P.push(1);
	//P???1
	f[1]=0;
	while(!P.empty()){			//
		d=P.front();
		//
		A[d]=1;
		//
		P.pop();				//
		for(i=1;i<=a;i++){
			//printf("%d %d %d\n",d,i,D[d][i]);//
			if(D[d][i]==-1){		//
			continue;			//
			}					//
			if(A[i]==1){		//
			continue;			//
			}					//
			P.push(i);			//
			f[i]=g[d]+1;
			g[i]=g[d]+1;
			A[i]=1;
			//printf("%d\n",P.back());
		}	
	}							//
	for(i=1;i<=a;i++){			//
	printf("%d %d\n",i, f[i]);	//
	}
	return 0;
}

C++: #include <iostream>
#include <queue>
using namespace std;
int c[101][102],ch[101];
queue<int> q;

int main(){
  int a,b,e,d,n,k;
  cin>>a;
  for(int i=1;i<=a;i++)ch[i]=-1;
  for(int i=0;i<a;i++){
    cin>>b>>e;
    c[b][0]=e;
    for(int j=1;j<=e;j++){
      cin>>d;
      c[b][j]=d;
    }
  }
  q.push(1);
  ch[1]=0;
  while(q.size()){
    n=q.front();q.pop();
    for(int i=1;i<=c[n][0];i++){
      if(ch[c[n][i]]==-1){
	q.push(c[n][i]);
	ch[c[n][i]]=ch[n]+1;
      }
    }
  }
  for(int i=1;i<=a;i++)cout<<i<<" "<<ch[i]<<endl;

  return 0;
}