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<queue>

using namespace std;

static const int N=100;
static const int INFTY=(1<<21);

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

void bfs(int s){
    queue<int> q;
    q.push(s);
    for(int i=0; i<n; i++){
        d[i]=INFTY;
    }
    d[s]=0;
    int u;
    while(!q.empty()){
        u=q.front(); 
        q.pop();
        for(int v=0; v<n; v++){
            if(M[u][v]==0){continue;}
            if(d[u]!=0){continue;}
            d[v]=d[u]+1;
            q.push(v);
        }
    }
    for(int i=0; i<n; i++){
        cout<<i+1<<" "<<((d[i]==INFTY)?(-1):d[i])<<endl;
    }
}

int main(){
    int u,v,k;
    cin>>n;

    for(int i=0; i<n; i++){
        for(int j=0; j<n; j++){
            M[i][j]=0;
        }
    }

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

C++: #include <iostream>
#include <cstdio>
#define MAX 101
using namespace std;

int n;
int a[MAX][MAX]={};
int d[MAX];

void track(int v,int depth){
  if(d[v]>depth||d[v]==-1){
    d[v]=depth;
  }else if(d[v]<depth){
    return;
  }
  for(int i=1;i<=n;i++){
    if(a[v][i]==1){
      track(i,depth+1);
    }
  }
}

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

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

  track(1,0);

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

C++: #include <bits/stdc++.h>
using namespace std;
#define MAX 105

int n, d[MAX];
vector<vector<int> > vec;
vector<int> ve;
queue<int> Q;

void bfs(int s) {
	for (int i = 1; i <= n; i++) {
		d[i] = -1;
	}
	d[s] = 0;
	Q.push(s);
	int now, cnt;
	while (!Q.empty()) {
		now = Q.front();
		Q.pop();
		for (cnt = 1; cnt <= vec[now][0]; cnt++) {
			if (d[vec[now][cnt]] == -1) {
				Q.push(vec[now][cnt]);
				d[vec[now][cnt]] = d[now] + 1;
			}
		}
	}
}

int main(void) {
	vec.push_back(ve);
	int u, k, v, i;
	cin >> n;
	for (i = 0; i < n; i++) {
		ve.clear();
		cin >> u >> k;
		ve.push_back(k);
		while (k--) {
			cin >> v;
			ve.push_back(v);
		}
		vec.push_back(ve);
	}

	bfs(1);

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

C++: using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define int long long
#define rep(i,n) for(int i = 0; i < (n); i++)
#define divup(a,b) ( ( (a) + ( (b) - 1u) ) / (b) ) // a/b の余り切り上げ
// #include <boost/multiprecision/cpp_int.hpp>
// using namespace boost::multiprecision;
const ll mod = 1000000007;
const ll mod9 = 1000000009;

ll d[109];
ll u[109];
ll k[109];
ll v[109][109];
struct Point{
    ll s,t;
};
queue<Point> S;

ll  bfs(){
    while(!S.empty()){
        ll n = S.front().s;
        ll t = S.front().t;
        S.pop();
        if(d[n]==0){
            d[n]=t;
        // cout<<" d "<<n<<" "<<t<<endl;
        }
        rep(i,k[n]){
            if(d[v[n][i]-1]==0) S.push({v[n][i]-1,t+1});
        }
    }
    return 0;
}

signed main(){
    ll n;
    cin>>n;
    rep(i,n){
        ll a;
        cin>>u[i]>>k[i];
        rep(j,k[i]){
            cin>>v[i][j];
        }
    }
    S.push({0,1});
    bfs();
    rep(i,n){
        d[i]--;
        printf("%lld %lld\n",i+1,d[i]);
    }
}

C++: #include <iostream>
#include <queue>
using namespace std;
struct id{
    int c[101];
    int p=0;
    int d=-1;
    int u=0;
};
int n,t=0;
id a[101];
queue<int> q;
void bps(int e){
    q.push(e);
    while(!q.empty()){
        int f=q.front();
        for(int i=1;i<=n;i++){
            if(a[f].c[i]==1&&a[i].u==0){
                a[i].d=a[f].d+1;
                q.push(i);
                a[i].u++;
            }
        }
        q.pop();
        a[f].u++;
    }
    
}

int main(){
    int x,y,z;
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>x>>y;
        for(int j=1;j<=y;j++){
            cin>>z;
            a[x].c[z]=1;
            a[z].p=x;
        }
    }
    a[1].d+=1;
    bps(1);
    for(int i=1;i<=n;i++){
        cout<<i<<" "<<a[i].d<<endl;
    }
    return 0;
}

C++: #include <iostream>
#include <queue>
#define INFTY -10000000
using namespace std;



int a[124][124] = {{}};
int d[124] = {};
int n;
void bfs(int k){
  queue <int> q;
  q.push(k);
  int u;


  while(!q.empty()){
    u = q.front(); q.pop();
    for(int v = 0;v < n;v++){
      if(a[u][v] == 0) continue;
      if(d[v] == INFTY) {
        d[v] = d[u] + 1;
        cout << v << " " << d[v] << endl;
      }
      q.push(v);
    }

  }
}

int main(){

  int u,k,x;
  cin >> n;

d[0] = 0;
for(int i = 1; i < n;i++) d[i] = INFTY;

  for(int i = 0;i < n;i++){
    cin >> u >> k;
    for(int j = 0;j < k;j++){
      cin >> x;
      a[u - 1][x - 1] = 1;
    }
  }

  bfs(0);

  for(int i = 0;i < n;i++){
    cout << i + 1 << " " << d[i] << endl;
  }
}