Go: package main

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

func main() {
	scn := bufio.NewScanner(os.Stdin)
	scn.Split(bufio.ScanWords)
	nextInt := func() int { scn.Scan(); r, _ := strconv.Atoi(scn.Text()); return r }
	w := bufio.NewWriter(os.Stdout)

	n := nextInt()
	vecs := make([][]int, n)
	for i := 0; i < n; i++ {
		u := nextInt()
		k := nextInt()
		for j := 0; j < k; j++ {
			vecs[u-1] = append(vecs[u-1], nextInt()-1)
		}
	}

	ds := make([]int, 0, n)
	for i := 0; i < n; i++ {
		ds = append(ds, -1)
	}

	q := make([]int, 0, n)
	q = append(q, 0)
	ds[0] = 0

	for len(q) > 0 {
		i := pop(&q)
		for _, v := range vecs[i] {
			if ds[v] == -1 {
				ds[v] = ds[i]+1
				q = append(q, v)
			}
		}
	}

	for i, d := range ds {
		fmt.Fprintln(w, i+1, d)
	}

	w.Flush()
}

func pop(q *[]int) int {
	v := (*q)[0]
	*q = (*q)[1:]
	return v
}

C++: #include<stdio.h>
#include<limits.h>
#define MAX 101
#define WHITE 0
#define GRAY 1
#define BLACK 2
#define TRUE 1
#define FALSE 0
/*void DFSVisit(int);
  void DFS(void);*/
void BFS(int);
int deQueue(void);
void enQueue(int);
int isEmpty(void);
int G[MAX][MAX];
int D[MAX];
int F[MAX];
int color[MAX];
int Q[MAX];
int n;
int time;
int head = 0, tail = 0;
main(){
  int i, j, m, k, value, start = 1;
  scanf("%d",&n);

  for(i = 1; i <= n; i++){
    for(j = 1; j <= n; j++){

      G[i][j] = 0;

    }
  }

  for(i = 1; i <= n; i++){

    scanf("%d %d", &k, &m);

    for(j = 1; j <= m; j++){

      scanf("%d",&value);

      G[i][value] = 1;
    }
  }
 
  BFS(start);

  for(i = 1; i <= n; i++)
    {
      if(D[i]==INT_MAX)D[i] = -1;
      printf("%d %d\n", i, D[i]);
    }

 return 0;

}




/*void DFS(void){
  int u;

  for( u = 1; u <= n; u++ ){

    color[u] = WHITE;

  }

  time = 0;

 for( u = 1; u <= n; u++ ){
   if( color[u] == WHITE )
     DFSVisit(u);

  }

}

void DFSVisit(int u){
  int v;

  color[u] = GRAY;

  time++;
 
  D[u] = time;

  for(v = 1; v <= n ; v++){

    if(G[u][v] == 1 && color[v] == WHITE)
      DFSVisit(v);
  }
  color[u] = BLACK;

  F[u] = ++time;
  }*/

void BFS(int start){
  int u, v;

  for(u = 2; u <= n; u++ ){

    color[u] =  WHITE;

    D[u] = INT_MAX;

  }

  color[start] = GRAY;

  D[start] = 0;

  enQueue(start);
  while(isEmpty() != FALSE){

    u = deQueue();

    for( v = 1; v <= n; v++ ){
      if(color[v] == WHITE && G[u][v] == 1){

	color[v] = GRAY;

	D[v] = D[u] + 1;

	enQueue(v);
      }
    }
  }
}

void enQueue(int x){

  Q[tail] = x;

    if(tail == 100)tail = 0;
    
    else tail ++; 

}

int deQueue(){

  int x;

  x = Q[head];

  if(head == 100)head = 0;

  else head++;

  return x;
}


int isEmpty(){
  if(tail == head)return FALSE;

  else return TRUE;
}

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[v]!=INFTY)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,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 <cstdio>
#include <queue>
using namespace std;
#define INF (1<<21)

int n, G[100][100], dist[100], visited[100];


int main(void) {
    int u, k, v, i, j;
    scanf("%d", &n);
    for (i = 0; i < n; i++)
        for (j = 0; j < n; j++) G[i][j] = 0;

    for (i = 0; i < n; i++) {
        scanf("%d %d", &u, &k);
        u--;
        for (j = 0; j < k; j++) {
            scanf("%d", &v);
            v--;
            G[u][v] = 1;
        }
    }
    
    for (i = 1; i < n; i++) {
        dist[i] = INF;
        visited[i] = 0;
    }
    dist[0] = 0;
    visited[0] = 1;

    queue<int> q;
    q.push(0);
    while (!q.empty()) {
        u = q.front();
        q.pop();
        for (i = 0; i < n; i++) {
            if (G[u][i] == 0 || visited[i] == 1) continue;
            q.push(i);
            visited[i] = 1;
            dist[i] = dist[u] + 1;
        }
    }

    for (i = 0; i < n; i++) {
        if (dist[i] == INF) dist[i] = -1;
        printf("%d %d\n", i + 1, dist[i]);
    }

    return 0;
}

C++: //Breadth First Search
#include <iostream>
#include <queue>

using namespace std;

static const int N = 100;

int d[N];

void bfs(vector<vector<int>> &graph, int u) {
    queue<int> q;
    q.push(u);
    d[u] = 0;

    while(!q.empty()) {
        int v = q.front();
        q.pop();
        for (auto w: graph[v]) {
            if(d[w] != -1) continue;
            q.push(w);
            d[w] = d[v] + 1;
        }
    }
}

int main() {
    int n;
    cin >> n;
    int u, k, v;
    vector<vector<int>> graph(n);
    for(int i=0; i<n; i++) {
        cin >> u >> k;
        for(int j=0; j<k; j++) {
            cin >> v;
            graph[u-1].push_back(v-1);
        }
    }
    for(int i=0; i<n; i++) d[i] = -1;

    bfs(graph, 0);

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

C++: #include<bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < (int)(n); i++)

#define N 100

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

queue<int> Q;

void bfs(int x){
    //初期化
    rep(i,n){
        d[i] = -1;
    }

    d[x] = 0;
    Q.push(x);

    while(!Q.empty()){
        int v = Q.front(); Q.pop();
        for(int i = 0; i < n; i++){
            if(M[v][i] == 1){
                if(d[i] == -1){
                    Q.push(i);
                    d[i] = d[v] + 1;
                }else{
                    d[i] = min(d[i], d[v] + 1);
                }
                
            }
        }
    }
}


int main(){
    cin >> n;

    rep(i,N)rep(j,N) M[i][j] = 0;

    int u, k, v;
    rep(i,n){
        cin >> u >> k;
        u--; //0オリジンに変換
        rep(j,k){
            cin >> v;
            v--; //0オリジンに変換
            M[u][v] = 1;
        }
    }

    bfs(0);

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

    return 0;
    
}

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

using namespace std;
int main(){
  int u, i, id, k, j;
  cin >> u;
  unordered_map<int, vector<int> > mymap;
  queue<vector<int> > myqueue;
  for (i = 0; i < u; ++i){
    cin >> id >> k;
    vector<int> points;
    for (j = 0; j < k; ++j){
      int a;
      cin >> a;
      points.push_back(a);
    }
    mymap[id] = points;
    if(id == 1){
      myqueue.push(points);
    }
  }
  
  bool visited[u+1];
  for (j = 1; j <= u; ++j){
    visited[j] = false;
  }
  visited[1] = true;

  int dist[u+1];
  for (j = 1; j <= u; ++j){
    dist[u] = -1;
  }
  dist[1] = 0;
  int d = 1;

  while(!myqueue.empty()){
    vector<int> combined;
    for (i = 0; i < myqueue.front().size(); ++i){
      if(!visited[myqueue.front()[i]]){
        dist[myqueue.front()[i]] = d;
        visited[myqueue.front()[i]] = true;
        if(combined.empty()){
          combined = mymap[myqueue.front()[i]];
        }else{
          combined.insert(combined.end(), mymap[myqueue.front()[i]].begin(), mymap[myqueue.front()[i]].end());
        }
      }
    }
    if(!combined.empty()){
      myqueue.push(combined);
    }
    myqueue.pop();
    d++;
  }

  for (j = 1; j <= u; ++j){
    cout << j << " " << dist[j] << endl;
  }

}