Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

//util
var sc = bufio.NewScanner(os.Stdin)

func nextStr() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func printList(list []int) {
	n := len(list)
	buf := bufio.NewWriter(os.Stdout)
	for _, v := range list[0 : n-1] {
		buf.Write([]byte(fmt.Sprintf("%d ", v)))
	}
	buf.Write([]byte(fmt.Sprintf("%d\n", list[n-1])))
	buf.Flush()
}

func max(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func min(a, b int) int {
	if a > b {
		return b
	} else {
		return a
	}
}

//solve
const INFTY = (1 << 21)
const MAX = 100
const WHITE = 0
const GRAY = 1
const BLACK = 2

var time, n int

//隣接行列
var M [MAX][MAX]int

//d[i]: 頂点1から頂点iまでの距離
var color, d [MAX]int

func bfs(s int) {
	var q []int
	q = append(q, s)
	for i := 0; i < n; i++ {
		d[i] = INFTY
	}
	//sは開始点なので、0をいれる
	d[s] = 0

	//キューが空になるまで、以下を繰り返す
	for len(q) > 0 {
		u := q[0]
		q = q[1:]
		for v := 0; v < n; v++ {
			if M[u][v] == 0 {
				continue
			}
			if d[v] != INFTY {
				continue
			}
			d[v] = d[u] + 1
			q = append(q, v)
		}
	}

	for i := 0; i < n; i++ {
		fmt.Printf("%d ", i+1)
		if d[i] == INFTY {
			fmt.Printf("%d\n", -1)
		} else {
			fmt.Printf("%d\n", d[i])
		}
	}
}

func main() {
	sc.Split(bufio.ScanWords)
	n = nextInt()
	for i := 0; i < n; i++ {
		u, k := nextInt(), nextInt()
		M[u-1][u-1] = 0

		//fmt.Println(u, k)
		if k > 0 {
			for j := 0; j < k; j++ {

				v := nextInt()
				M[u-1][v-1] = 1

			}
		}

	}

	bfs(0)

}

C++: #define _GLIBCXX_DEBUG
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ALL(v) v.begin(), v.end()
typedef long long ll;

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

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

#define white 0
#define gray 1

int M[101][101];
int d[101],color[101];
queue<int> q;
int a,n;

void bfs(int u){
  color[u]=gray;
  q.push(u);
  while(!q.empty()){
    a=q.front();
    q.pop();
    for(int v=1;v<=n;v++){
      if(M[a][v]==1 && color[v]==white){
        color[v]=gray;
        d[v]=d[a]+1;
        q.push(v);
      }
    }
  }
}

int main(){
  int x,y,z;
  cin>>n;
  
  rep(i,101){
    rep(j,101) M[i][j]=0;
  }
  
  rep(i,101){
    d[i]=-1;
    color[i]=white;
  }
  d[1]=0;
  
  rep(i,n){
    cin>>x>>y;
    rep(j,y){
      cin>>z;
      M[x][z]=1;
    }
  }
  
  bfs(1);
  for(int i=1;i<n+1;i++) cout<<i<<" "<<d[i]<<endl;
  
  return 0;
}

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

struct graph {
	struct node {vector<int> v; int d = -1;};
	map<int, node> nodes;

	void read_all() {
		int n, id, k, v;
		cin >> n;
		while (n--) {
			cin >> id >> k;
			if (k)
				while (k--) {
					cin >> v;
					nodes[id].v.push_back(v);
				}
			else
				nodes[id].v = {};
		}
	}
	void traverse(int id) {
		nodes[id].d = 0;
		queue<int> q;
		q.push(id);
		while (!q.empty()) {
			node &n = nodes[q.front()];
			q.pop();
			for (int x: n.v) {
				if (nodes[x].d != -1)
					continue;
				else
					nodes[x].d = n.d + 1;
				q.push(x);
			}
		}
	}
	void display_all() {
		for (auto &n: nodes)
			cout << n.first << " " << n.second.d << endl;
	}
};

int main() {
	graph g;
	g.read_all();
	g.traverse(1);
	g.display_all();
}

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

int main(){
  int u,k,v;
  cin>>n;
  for(int i=0;i<n;i++){
    for(int j=0;j<k;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 <cmath>
#include <queue>
#include <iostream>
using namespace std;

int G[110][110] = {0};
int n;
int D[110] = {0};
void bfs(int src){
 queue<int> Q;
 Q.push(src);
 D[src] = 0;
 while(! Q.empty()){
  int cur = Q.front();
  Q.pop();
  for(int i=1; i<=n; i++){
   if(G[cur][i]==1 && D[i]==0 && i!=1){
    D[i] = D[cur]+1;
    Q.push(i);
   }
  }
 }

 for(int i=1; i<=n; i++){
  if(i!=1 && D[i]==0){
   D[i]=-1;
  }
  cout << i << " " << D[i] << endl;
 }
}

int main(){
 cin >> n;
 int u, k;
 int v[100000];
 for(int i=0; i<n; i++){
  cin >> u >> k;
  for(int j=0; j<k; j++){
   cin >> v[j];
   G[i+1][v[j]] = 1;
  }
 }
 bfs(1);
}

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

using namespace std;

#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2
#define INFINITY -1

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

void bfs_visit(int u){

  queue<int> Q;
  color[u] = GRAY;
  Q.push(u);

  d[u] = 0;

  int present;
  while( !Q.empty() ){
    present = Q.front();
    Q.pop();
    color[present] = BLACK;

    for(int v=0;v<n;v++){
      if( M[present][v] == 1 && color[v] == WHITE ){
        Q.push(v);
        color[v] = GRAY;
        d[v] = d[present] + 1;
      }
    }  
  }
}

void bfs(int u){

  for(int i=0;i<n;i++){
    color[i] = WHITE;
    d[i] = INFINITY;
  }

  bfs_visit(u);

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


int main(void){

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

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

  bfs(0);

  return 0;
}

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

using namespace std;

int main(){
	int n, u, k, v;
	int D[100];
	bool adj[100][100] = {};
	int pushed[100] = {};
	cin >> n;
	for (int i = 1; i <= n; i++){
		cin >> u >> k;
		for (int j = 1; j <= k; j++){
			cin >> v;
			adj[u][v] = true;
		}
	}
	for (int i = 1; i <= n; i++){
		D[i] = -1;
	}
	queue<int> Q;
	Q.push(1);
	D[1] = 0;
	pushed[1] = 1;
	while(!Q.empty()){
		int m = Q.front();
		Q.pop();
		for (int i = 1; i <= n; i++){
			if (adj[m][i] == true && pushed[i] == 0){
				D[i] = D[m]+1;
				Q.push(i);
				pushed[i] = 1;
			}
		}
	}
	
	for (int i = 1; i < n+1; i++){
		cout << i << ' ' << D[i] << endl;
	}
}

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

#define rep(i, n) for (int i = 0; i < (int)(n); ++i)

const int INF = 1 << 21;

int main() {
  int n;
  std::cin >> n;

  int a[n][n];

  rep(i, n) rep(j, n) a[i][j] = 0;

  rep(i, n) {
    int u, k;
    std::cin >> u >> k;
    rep(j, k) {
      int v;
      std::cin >> v;
      a[u - 1][v - 1] = 1;
    }
  }

  int d[n];
  rep(i, n) d[i] = INF;
  d[0] = 0;

  std::queue<int> q;
  q.push(0);

  while (!q.empty()) {
    int u = q.front();
    q.pop();
    rep(j, n) {
      if (a[u][j] && d[j] == INF) {
        d[j] = d[u] + 1;
        q.push(j);
      }
    }
  }

  rep(i, n) std::cout << i + 1 << ' ' << (d[i] == INF ? -1 : d[i]) << '\n';

  return 0;
}

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

int n,u,k,v;
int g[102][102];
int d[102];
int sn[102];
int cnt=0;
int x,siz;

queue<int>q;

int main(){
  cin>>n;
  memset(g,0,sizeof(g));
  for(int i=1;i<=n;i++){
    cin>>u>>k;
    d[i]=-1;
    sn[i]=0;
    for(int j=1;j<=k;j++){
      cin>>v;
      g[u][v]=1;
    }
  }
  
  q.push(1);

  while(!q.empty()){

    siz=q.size();

    for(int i=0;i<siz;i++){
      
      x=q.front();
      q.pop();
      
      sn[x]=1;
      if(d[x]==-1)d[x]=cnt;
      
      for(int j=1;j<=n;j++){
	
	if(g[x][j]==1 && sn[j]==0){
	  q.push(j);
	}
      
      }

    }

    cnt++;

  }

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

  }

}