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> // cout, endl, cin
#include <string> // string, to_string, stoi
#include <vector> // vector
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <utility> // pair, make_pair
#include <tuple> // tuple, make_tuple
#include <cstdint> // int64_t, int*_t
#include <cstdio> // printf
#include <map> // map
#include <queue> // queue, priority_queue
#include <set> // set
#include <stack> // stack
#include <deque> // deque
#include <unordered_map> // unordered_map
#include <iomanip>
#include <unordered_set> // unordered_set
#include <bitset> // bitset
#include <cctype> // isupper, islower, isdigit, toupper, tolower
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
using namespace std;
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; }
const int INF = 1000000000;
const int MOD = 1000000007;

typedef pair<int, int> P;
int myAbs(int num) {
    if (num > 0)
        return num;
    else
        return -num;
}

long long gcd(long long a, long long b) {
    if (b == 0) return a;
    else return gcd(b, a % b);
}
long long lcm(long long a, long long b) {
    return a * b / gcd(a, b);
}

using Graph = vector<vector<int>>;
//再帰とかグラフを使うときは予めNの最大値のグローバル配列を取っておく
int N;
bool E[101][101];
vector<bool> seen;
typedef pair<int, int> P;
int D[101];
//頂点状態を表すcolor[]において、0は未訪問、1は訪問中、2は完了を表す。
int color[101];
int find_time = 0;

void bfs(int start) {
    //全頂点を未訪問にして距離も初期化(INF)
    for (int i = 0; i < 101; i++) D[i] = -1;
    queue<int> Q;
    //最初の頂点をキューに入れる
    Q.push(start);
    int v;
    //最初の頂点は距離0
    D[start] = 0;
    //キューが空になるまで探索
    while (!Q.empty()) {
        v = Q.front();
        Q.pop();
        for (int i = 1; i <= N; i++) {
            //今訪問している頂点vから辺があるか&&すでに訪問済み(距離がINFではない)を確認
            if (!E[v][i]) continue;
            if (D[i] != -1) continue;
            //未訪問かつ辺があったなら元の頂点の距離に1を足す
            D[i] = D[v] + 1;
            //発見した頂点をキューに入れて再度探索
            Q.push(i);
        }
    }
    for (int i = 1; i <= N; i++) {
        cout << i << " " << D[i] << endl;
    }
}

int main() {
    cin >> N;
    int u, k,v;
    //頂点を1から入力(0ではなく)
    //辺の有無をbool E[][]で管理
    for (int i = 0; i < N; i++) {
        cin >> u >> k;
        for (int j = 0; j < k; j++) {
            cin >> v;
            E[u][v] = true;
        }
    }
    //探索開始頂点を引数にして開始
    bfs(1);

}

C++: #include <cstdio>
#include <cstring>
#include <queue>

using namespace std;
int g[101][101], d[101];
bool vis[101];
int dis = 0, n;

void bfs(int u)
{
  queue<int> Q;
  Q.push(u);
  vis[u] = true;
  d[u] = 0;
  while (!Q.empty())
  {
    int tmp = Q.front();
    Q.pop();
    for (int i = 0; i < n; i++)
    {
      if (g[tmp][i] != 0 && !vis[i])
      {
        vis[i] = true;
        Q.push(i);
        d[i] = d[tmp] + 1;
      }
    }
  }
}

int main()
{
  memset(g, 0, sizeof(g));
  memset(d, -1, sizeof(d));
  memset(vis, false, sizeof(vis));
  scanf("%d", &n);
  for (int i = 0; i < n; i++)
  {
    int u, adj_num;
    scanf("%d%d", &u, &adj_num);
    while (adj_num--)
    {
      int v;
      scanf("%d", &v);
      g[u - 1][v - 1] = 1;
    }
  }
  bfs(0);
  for (int i = 0; i < n; i++)
  {
    printf("%d %d\n", i + 1, d[i]);
  }
}

C++: #include <cstdio>
#include <iostream>
#include <cmath>
#include <ctype.h>
#include <string>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <map>
#include <queue>
#include <utility>
#include <vector>
#include <set>
#include <list>
#include <cstring>
#include <stack>

using namespace std;

#define mod 1000000007

int main()
{
	int n;
	int graph[101][101] = {};
	cin >> n;
	int ans[101] = {};
	for(int i = 0; i < n; i++){
		ans[i] = -1;
		int u, k;
		cin >> u >> k;
		u--;
		for(int j = 0; j < k; j++){
			int v;
			cin >> v;
			v--;
			graph[u][v] = 1;
		}
	}
	queue<int> qu;
	qu.push(0);
	ans[0] = 0;
	while(!qu.empty()){
		int tmp = qu.front();
		qu.pop();
		for(int i = 0; i < n; i++){
			if(ans[i] == -1 && graph[tmp][i] > 0){
				ans[i] = ans[tmp] + 1;
				qu.push(i);
			}
		}
	}
	for(int i = 0; i < n; i++){
		cout << i + 1 << " " << ans[i] << endl;
	}
}

C++: # -*- coding: utf-8 -*-
from collections import deque

N = int(input())
adj = [[0]*N for _ in range(N)]
unsearched = set(range(1, N))
result = {n:-1 for n in range(N)}

for n in range(N):
    inp = list(map(int, input().split()))
    for i in inp[2:]:
        adj[inp[0]-1][i-1] = 1

que = deque([[0, 0]]) # edge distance


while len(que):
    q = que.pop()
    result[q[0]] = q[1]
    next_ = [[i, q[1] + 1] for i, a in enumerate(adj[q[0]]) if (a==1) & (i in unsearched)]
    unsearched = unsearched.difference([i[0] for i in next_])
    que.extendleft(next_)

for n in range(N):
    print("{} {}".format(n+1, result[n]))