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<algorithm>
#include<queue>
using namespace std;
static const int MAX=10000;
static const int INFTY = (1<<20);
static const int WHITE=0;
static const int GRAY=1;
static const int BLACK=2;

int n;
vector<pair<int,int> > adj[MAX];
void dijkstra(){
  priority_queue<pair<int,int> > PQ;
  int color[MAX];
  int d[MAX];
  for(int i=0;i<n;i++){
    d[i]=INFTY;
    color[i]=WHITE;
  }
  d[0]=0;
  PQ.push(make_pair(0,0));
  color[0]=GRAY;

  while(!PQ.empty()){
    pair<int,int>f=PQ.top();PQ.pop();
    int u=f.second;
    color[u]=BLACK;
    if(d[u]<f.first*(-1))continue;
    for(int j=0;j<adj[u].size();j++){
      int v=adj[u][j].first;
      if(color[v]=BLACK)continue;
      if(d[v]>d[u]+adj[u][j].second){
        d[v]=d[u]+adj[u][j].second;
        PQ.push(make_pair(d[v]*(-1),v));
        color[v]=GRAY;
      }
    }
  }
  for(int i=0;i<n;i++){
    cout<<i<<" "<<(d[i]==INFTY ? -1:d[i])<<endl;
  }
}

int main(){
  int k,u,v,c;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>u>>k;
    for(int j=0;j<k;j++){
      cin>>v>>c;
      adj[u].push_back(make_pair(v,c));
    }
  }
  dijkstra();
  return 0;
}

C++: #include<iostream>
#include<queue>
#define N 101
using namespace std;
int A[N][N];
bool visited[N];
int n;
int d[N];
int distance;
queue<int> node;

void bfs(){
    while(!node.empty()){
        int temp=node.front();
        for(int i=0;i<n;i++){
            if(temp==i) continue;
            if(!visited[i] && A[temp][i]==1){
                d[i]=d[temp]+1;
                visited[i]=true;
                node.push(i);
            }
        }
        node.pop();
    }
}

int main(){
    int k,num;
    int e;
    cin>>n;
    for(int i=0;i<n;i++){
        visited[i]=false;
        d[i]=-1;
        for(int j=0;j<n;j++)
            A[i][j]=0;
    }
    for(int i=0;i<n;i++){
        cin>>k;
        k--;
        cin>>num;
        for(int j=0;j<num;j++){
            cin>>e;
            e--;
            A[k][e]=1; //A[e][k]=1;
        }
    }

    node.push(0);
    visited[0]=true;
    d[0]=0;
    bfs();

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

    return 0;

}

C++: #include<iostream>
using namespace std;
#include<queue>
queue<int>mp;
#define N 105
#define INF 1<<21
int a[N][N];
int d[N];
int n;

void bfs(int s){
	mp.push(s);
	for (int i = 1;i <= n;i++){
		d[i] = INF;
	}
	d[s] = 0;
	int u;
	while (!mp.empty()){
		u = mp.front();
		mp.pop();
		for (int v = 1;v <= n;v++){
			if (a[u][v] == 0) continue;
			if (d[v] != INF) continue;
			d[v] = d[u] + 1;
			mp.push(v);
		}
	}
	for (int i = 1 ;i <= n;i++){
		if (d[i] == INF){
			cout << i << " " << "-1" << endl; 
		}
		else{
			cout << i << " " << d[i] << endl;
		}
	}
}

int main()
{
	cin >> n;
	for (int i = 1;i <= n;i++){
		for (int j = 1;j <= n;j++){
			a[i][j] = 0;
		}
	}
	int x,m,y;
	for (int i = 1;i <= n;i++){
		cin >> x >> m;
		while (m--){
			cin >> y;
			a[x][y] = 1;
		}
	}
	bfs(1);
	return 0;
}

C++: #include <bits/stdc++.h>
#define FOR(i,a,b) for(int i= (a); i<(b); i++)
#define REP(i,n) for(int i=0;i < (n);i++)
#define ALL(obj) (obj).begin(),(obj).end()
using namespace std;

const long long INF = 1LL << 60;
const int MOD = (int)1e9 + 7;
typedef long long ll;
//約数列挙
vector<long long> divisor(long long n) {
    vector<long long> ret;
    for (long long i = 1; i * i <= n; i++) {
        if (n % i == 0) {
            ret.push_back(i);
            if (i * i != n) ret.push_back(n / i);
        }
    }
    //sort(ret.begin(), ret.end()); // 昇順に並べる
    return ret;
}
vector<vector<int>> graph;
vector<int> ans;
signed main () {
    int n;scanf("%d",&n);
    graph.assign(n,vector<int>(n));
    ans.assign(n,-1);
    REP(i,n){
        int id,tmp;scanf("%d %d",&id,&tmp);
        REP(j,tmp){
            int t;scanf("%d",&t);
            graph[i].push_back(t-1);
        }
    }
    queue<pair<int,int>> q;
    q.push(make_pair(0,0));ans[0] = 0;
    while(!q.empty()){
        pair<int, int> tmp = q.front();q.pop();
        int ind = tmp.first;int cnt = tmp.second;
        for(int next : graph[ind]){
            if(ans[next]!=-1)continue;
            ans[next] = cnt+1;
            q.push(make_pair(next, cnt+1));
        }
    }
    REP(i,n){
        printf("%d %d\n",i+1,ans[i]);
    }
}