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<iostream>
#include<algorithm>
#include<queue>
#define MAX 101
using namespace std;
int n,d[MAX],color[MAX],A[MAX][MAX];
queue<int> Number_of_vertices;
void input(void){
    cin >> n;
    for(int i=0;i<n;i++){
        d[i] = -1;
        color[i] = 0;
        A[i][i] = 0;
    }
    for(int i=0;i<n;i++){
        int id,adj;
        cin >> id >> adj;
        id--;
        if(i==0){
            Number_of_vertices.push(id);
            d[id] = 0;
            color[id] = 1;
        }
        for(int j=0;j<adj;j++){
            int k;
            cin >> k;
            A[id][--k] = 1;
        }
    }
}
void Breadth_First_Search(void){
    while(!Number_of_vertices.empty()){
        int u = Number_of_vertices.front();
        Number_of_vertices.pop();
        for(int i=0;i<n;i++){
            if(color[i]==0 && A[u][i]==1){
                d[i] = d[u] + 1;
                color[i] = 1;
                Number_of_vertices.push(i);
            }
        }
    }
}
void print(void){
    for(int i=0;i<n;i++){
        cout << i + 1 << ' ' << d[i] << endl;
    }
}
int main(void){
    input();
    Breadth_First_Search();
    print();
    return 0;
}

C++: #include<stdio.h>
#define N 101
#define WHITE 2
#define GRAY 1
#define BLACK 0
#define INF 1000000

 
int n, h= 0, t = 0;
int col[N], d[N], a[N][N], e[N]; 

int Que[N];



 int Dequeque(){
  h++;
  return Que[h - 1];
}
void Enqueque(int b){
  Que[t] = b;
  t++;
}
 
void BFS(int s){
  int i, u, next;
  for(i = 1; i < n+1; i++){
      col[i] = WHITE;


      d[i] = -1;
  }
 
  col[s] = GRAY;
  d[s] = 0;
  Enqueque(s);
 
  while(h != t){
    u = Dequeque();
    for(i = 1; i <= n; i++){
      if((col[i] == WHITE) && (a[u][i] == 1)){


    col[i] = GRAY;
    d[i] = d[u] + 1;
    Enqueque(i);
      }
    }
   

    col[u] = BLACK;
  }
}
 

  
main(){
 
  scanf("%d", &n);
 
  int i, u, j,y=1;



  /*配列の初期化*/
  for(i = 1; i < n+1; i++){
    for(j = 1; j < n+1; j++){
     

 a[i][j] = 0;

    }
  }

  int x; 
  for(i = 1; i < n+1; i++){
    scanf("%d%d", &u, &e);
    for(j = 1; j <= e; j++){
      scanf("%d", &x);
      a[i][x] = 1;
    }
  }
 
  BFS(y);
   
  for(i = 1; i < n+1; i++){
    printf("%d ", i);
    printf("%d\n", d[i]);
  }
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define repd(i,a,b) for (int i=(a);i<(b);i++)
#define rep(i,n) repd(i,0,n)
#define all(x) (x).begin(),(x).end()
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
typedef long long ll;
const long long INF = 1e9;
typedef pair<int, int> P;
int main()
{
    int N;
    cin >> N;
    vector<vector<int>> G(N);
    rep(i, N) {
        int u, k;
        cin >> u >> k;
        rep(j, k) {
            int v;
            cin >> v;
            G[u - 1].push_back(v - 1);
        }
    }

    vector<int> d(N, INF);
    d[0] = 0;
    queue<int> que;
    que.push(0);
    while (!que.empty()) {
        int v = que.front(); que.pop();
        for (auto to : G[v]) {
            if (d[to] != INF) continue;
            d[to] = d[v] + 1;
            que.push(to);
        }
    }

    rep(i, N) {
        cout << i + 1 << " " << (d[i] == INF ? -1 : d[i]) << endl;
    }
    return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
int main()
{
    int n;
    scanf("%d", &n);
    vector<vector<int>> a(n, vector<int>(0, 0));
    vector<int> b(n,-1);
    b[0] = 0;
    for (int i = 0, u, k; i < n; i++)
    {
        scanf("%d %d", &u, &k);
        u--;
        for (int j = 0, v; j < k; j++)
        {
            scanf("%d", &v);
            a[u].push_back(--v);
        }
    }
    queue<int> c;
    c.push(0);
    for (int t; !c.empty(); )
    {
        t = c.front();
        c.pop();
        for (int i = 0; i < a[t].size(); i++)
        {
            if (b[a[t][i]] == -1)
            {
                c.push(a[t][i]);
                b[a[t][i]] = b[t] + 1;
            }
        }
    }
    for (int i = 0; i < n; i++)
    {
        printf("%d %d\n", i + 1, b[i]);
    }
}

C++: #include <iostream>
#include <algorithm>
#include <string>
#include <stack>
#include <cstdlib>
#include <queue>
#include <vector>
#include <set>
#include <stdio.h>
using namespace std;
int n,m,l,p;
int a[100][100];
int D[100];
void bfs( int src) {
	queue<int> Q;
	Q.push(src);
	D[src]=0;
	while( ! Q.empty() ) {
		int cur = Q.front();
		Q.pop();
		for(int dst = 0; dst < n; dst++ ) {
			if( D[dst] < 0 && a[cur][dst] == 1 ) {
				D[dst] = D[cur] + 1;
				Q.push(dst);
			}
		}
	}
	for (int i = 0; i < n;i++) {
	cerr << i+1 <<  " " << D[i] <<  endl;
	}
}

int main() {
	cin >> n;
	for ( int i = 0;i < n;i++) {
		D[i] = -1;
		for(int j= 0; j < n;j++) {
			a[i][j] = 0;
		}
	}
	for (int i = 0;i < n; i++){
		cin >> m;
		cin >> l;
		for(int j = 0; j < l;j++) {
			cin >> p;
			a[m-1][p-1] = 1;
		}
	}
	bfs(0);
}

C++: #include <iostream>
using namespace std;
#define INF 9999999

int dis[101]; //距離を格納
bool check[101];//訪問済みチェック
int main(){
  int n;
  cin>>n;
  fill(dis,dis+101,INF);
  dis[1]=0;
  check[1]=true;
  for(int i=0;i<n;i++){
    int u,k,v;
    cin>>u>>k;
    for(int j=1;j<=k;j++){
      cin>>v;
      if(check[v]){//訪問済みならば
        continue;
      }else{
        check[v]=true;
      }
      dis[v]=dis[u]+1;
    }
  }

  //表示部
  for(int i=1;i<=n;i++){
    cout<<i<<" ";
    if(dis[i]==INF)cout<<-1<<"\n";
    else  cout<<dis[i]<<"\n";
  }
}

C++: #include<iostream>
#include<queue>
using namespace std;
#define max 100

int n;
int aa[max][max];
int ans[max];
int color[max];
int p[max];
queue<int> q;

void bfs(int u) {
	for (int i = 0; i < n; i++) {
		if (aa[u - 1][i] == 1 && color[i] != 1) {
			q.push(i + 1);
			color[i] = 1;
			p[i] = u;
		}
	}
	while (!q.empty()) {
		int x = q.front(); q.pop();
		ans[x - 1] = ans[p[x-1]-1] + 1;
		bfs(x);
	}
}

int main()
{
	for (int i = 0; i < max; i++) {
		ans[i] = 0;
		color[i] = 0;
		p[i] = -1;
	}
	cin >> n;
	for (int i = 0; i < max; i++) {
		for (int j = 0; j < max; j++) {
			aa[i][j] = 0;
		}
	}

	for (int i = 0; i < n; i++) {
		int id;
		cin >> id;
		int num;
		cin >> num;
		for (int j = 0; j < num; j++) {
			int num1;
			cin >> num1;
			aa[id - 1][num1 - 1] = 1;
		}
	}

	bfs(1);

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

	return 0;
}