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>
#define REP(i, n) for (int (i) = 0; (i) < (int)(n); i++) 
#define FOR(i, a, b) for(int (i) = a; (i) < (int)b; i++)
#define RREP(i, n) for(int (i)=((int)(n)-1); (i)>=0; i--)
#define RFOR(i, a, b) for(int (i) =((int)(b)-1); (i)>=(int)a; i--)
#define ALL(v) (v).begin(),(v).end()
#define MOD 1000000007
#define NIL -1
#define FI first
#define SE second
#define MP make_pair
#define PB push_back
#define SZ(x)  (int)x.size()
#define SP(x)  setprecision((int)x)


using namespace std ;
typedef long long ll;
using Graph = vector<vector<int>>;
typedef vector<int> vint;
typedef vector<vint> vvint;
typedef vector<string> vstr;
typedef pair<int, int> pii;
const int INF = 1e9;
const ll LINF = 1e18;
const double EPS = 1e-9;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
ll gcd(ll a, ll b) {return b ? gcd(b, a % b) : a;} //最大公約数
ll lcm(ll a, ll b) {return a / gcd(a, b) * b;} //最小公倍数

//-------------------------------------------------
// 
void yes(){
  cout <<"Yes"<<endl ;
}
void no(){
  cout <<"No"<<endl ;
}


//-------------------------------------------------
// メモ
/*






*/
//-------------------------------------------------


int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  int n ;
  cin >> n ;
  vint d(n,-1) ;
  vint seen(n,0) ;
  queue<int> Q ;
  vvint gra(n) ;
  for(int i=0;i<n;i++){
    int a, b;
    cin >> a >> b;
    for(int j=0;j<b;j++){
      int c ;
      cin >> c ;
      gra[a-1].PB(c-1) ;
    }
  }
  
  Q.push(0) ;
  seen[0] = 1 ;
  d[0] = 0 ;
  
  while(!Q.empty()){
    int k = Q.front() ;
    for(int i=0;i<SZ(gra[k]);i++){
      if(seen[gra[k][i]]==0){
        Q.push(gra[k][i]) ;
        seen[gra[k][i]] = 1 ;
        d[gra[k][i]] = d[k] + 1 ;
      }
    }
    Q.pop() ;
  }
  
  for(int i=0;i<n;i++){
    cout << i+1 <<" "<<d[i] <<endl ;
  }
 
  return 0 ;
}

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

int *d;
int *k;
int **a;

void bfs(){
    int i, v, u;
    queue<int> q;
    q.push(1);
    d[1] = 0;
    while(!q.empty()){
        u = q.front();
        q.pop();
        for(i=0;i<k[u];i++){
            v = a[u][i];
            if(d[v]<0){
                q.push(v);
                d[v] = d[u] + 1;
            }
        }
    }
}

int main(){
    int i, j, n, u, v;
    scanf("%d",&n);
    d = (int *)malloc(sizeof(int)*(n+1));
    k = (int *)malloc(sizeof(int)*(n+1));
    a = (int **)malloc(sizeof(int *)*(n+1));
    for(i=0;i<=n;i++)d[i] = -1;

    for(i=0;i<n;i++){
        scanf("%d",&u);
        scanf("%d",k+u);
        a[u] = (int *)malloc(sizeof(int)*k[u]);
        for(j=0;j<k[u];j++){
            scanf("%d",&v);
            a[u][j] = v;
        }
    }

    bfs();

    for(i=1;i<=n;i++)printf("%d %d\n",i,d[i]);

    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,n) for(int i=0;i<n;i++)
#define MAX 100
#define Black 1
#define White 0

int f[MAX];
int adj[MAX][MAX];
int n;

void bfs(int r){
    rep(i,n)f[i]=-1;
    queue<int> Q;
    Q.push(r);
    f[r]=0;
    while(!Q.empty()){
        int u=Q.front();Q.pop();
        rep(i,n){
            if(adj[u][i]==1&&f[i]==-1){
                f[i]=f[u]+1;
                Q.push(i);
            }
        }
    }
    rep(i,n){
        printf("%d %d\n",i+1,f[i]);
    }
}

int main(){
    int id,k,node;
    cin>>n;
    rep(i,n)rep(j,n)adj[i][j]=0;
    rep(i,n){
        scanf("%d %d",&id,&k);
        id--;
        rep(j,k){
            scanf("%d",&node);
            node--;
            adj[id][node]=1;
        }
    }
    bfs(0);
    return 0;
}

C++: #include <bits/stdc++.h>
#define INF 10000000000
using namespace std;

struct edge {int to, cost;};
//=============dijkstra============================
vector<long long> dijkstra(int s, int V, vector<vector<edge>> G)
{
  vector<long long> d(V, INF);
  typedef pair<long long, int> P;// first は最短距離　second は頂点の番号
  priority_queue<P, vector<P>, greater<P>> que;
  d.at(s) = 0;
  que.push(P(0, s));
  while (!que.empty())
  {
    P p = que.top();
    que.pop();
    int v = p.second;
    if (d.at(v) < p.first) continue;
    for (int i = 0; i < G.at(v).size(); ++i)
    {
      edge e = G.at(v).at(i);
      if (d.at(e.to) > d.at(v) + e.cost)
      {
        d.at(e.to) = d.at(v) + e.cost;
        que.push(P(d.at(e.to), e.to));
      }
    }
  }
  return d;
}
//=================================================


int main()
{
  int n;
  cin >> n;
  vector<vector<edge>> G(n, vector<edge>(0));
  for (int i = 0; i < n; ++i)
  {
    int u, k;
    cin >> u >> k;
    for (int j = 0; j < k; ++j)
    {
      int v;
      cin >> v;
      G.at(u - 1).push_back({v - 1, 1});
    }
  }
  vector<long long> ans = dijkstra(0, n, G);
  for (int i = 0; i < n; ++i)
  {
    if (ans.at(i) == INF)
    {
      cout << i + 1 << ' ' << -1 << endl;
    }
    else
    {
      cout << i + 1 << ' ' << ans.at(i) << endl;
    }
  }
}