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

using namespace std;

int D[110]={0};
void bfs(int src,int n,int g[110][110]){

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



int main() {
int n,g[110][110]={0};
cin>>n;
int j,num,t;
for(int k=0;k<n;k++){
cin>>j>>num;
for(int kk=0;kk<num;kk++){
	cin>>t;
	g[k][t-1]=1;
}
}
bfs(0,n,g);
for(int a=0;a<n;a++){
	cout<<a+1<<" "<<D[a]<<endl;
}
	return 0;
}

C++: #include<iostream>
#include<algorithm>
using namespace std;

int head, tail;
int Q[100000]; //queue
int n;
int d[110]; //distance
bool a[110][110] = {}; //adjacency matrix

//queue
void enqueue(int x){
  
  Q[tail] = x;

  if(tail + 1 == 100000) tail = 0;
  else tail++;
}

int dequeue(){
  
  int x = Q[head];

  if(head + 1 == 100000) head = 0;
  else head++;

  return x;
}

void bfs(int u){
  
  enqueue(u);
  d[u] = 0;
  
  while(head != tail){
    int p = Q[head];
    dequeue();
    
    for(int i = 2;i <= n;i++){
      //if i is adjoining p and have not been visited, calculate the distance
      if(a[p][i] && d[i] == 0){
        enqueue(i);
        d[i] = d[p] + 1;
      }
    }
  }
}

int main(){
  
  int u, k, v;

  //input
  cin >> n;
  for(int i = 0;i < n;i++){
    cin >> u >> k;
    for(int j = 0;j < k;j++){
      cin >> v;
      a[u][v] = true;
    }
  }
  
  bfs(1);

  //output
  for(int i = 1;i <= n;i++){
    if(d[i] || i == 1) cout << i << " " << d[i] << endl;
    else cout << i << " " << -1 << endl;
  }
  
  return 0;
}

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

const int mod = 1e9+7;
const int INF = 2000000;

int main() {
    int n;
    cin >> n;
    vector<vector<int>> G(n+1);
    for(int i=1;i<=n;++i) {
        int u,k;
        cin >> u >> k;
        for(int j=0;j<k;++j) {
            int v;
            cin >> v;
            G[u].push_back(v);
        }
    }
    queue<int> q;
    vector<int> cnt(n+1,-1);
    cnt[1] = 0;
    q.push(1);
    while (!q.empty())
    {
        int u = q.front();
        q.pop();
        for(int i:G[u]) {
            if(cnt[i] != -1) continue;
            cnt[i] = cnt[u] + 1;
            q.push(i);
        }
    }
    for(int i=1;i<=n;++i) cout << i << " " << cnt[i] << endl;
}