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 <fstream>
#include <string>
#include <cmath>
#include <vector>
#include <algorithm>
#include <functional>
#include <cstdio>
#include <cstdlib>
#include <iomanip>
#include <cctype>
#include <bits/stdc++.h>
#include <queue>

using namespace std;
// for loop
#define F(i, L, R) for(long i = L; i < R; i++)
#define FE(i, L, R) for(long i = L; i <= R; i++)
// for (reversed)
#define FR(i, L, R) for(long i = L; i > R; i--)
#define FRE(i, L, R) for(long i = L; i >= R; i--)

// data types
#define Int long
#define ul unsigned long
#define ll long long
#define ull unsigned long long
#define ui unsigned int
#define us unsigned shoft

// vectors
typedef vector<int> vi;
typedef vector<long> vl;
typedef vector<vi> vvi;
typedef pair<int, int> ii;
#define ALL(c) (c).begin(),(c).end()
#define last(vec) vec.size()-1
#define lastEle(vec) vec[last(vec)]
#define pb push_back
#define InputV(a, n) F(i,0,n){long l; cin >> l; a.pb(l);}

// debug
#define DBG(vari) cerr<<#vari<<" = "<<(vari)<<endl;
#define printA(a, L, R) FE(i, L, R) cout << a[i] << (i==R?'\n':' ')
#define printAF(a, L) printA(a, 0, L-1)
#define printV(a) printA(a, 0, a.size()-1)

// utils
#define char2int(c) (c-'0')
#define bit(x, i) (x&(1<<i))
#define space ' '
#define PI 3.14159265358979323

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;
}

void printM(vector<vector<int> > &vec, long height, long width){
    F(i, 0, height){
        F(j, 0, width){
            cout << vec[i][j] << space;
        }
        cout << endl;
    }
}

vector<int> seen;
vector<int> done;
vector<int> cost;
int timestamp;

// Graph: グラフを表した隣接リスト
// v: 何番目のノードを訪問するのか
void dfs(vector<vector<int> > &Graph, int v){
    timestamp++;
    seen[v] = timestamp; //訪問済みにする

    // 隣接するノードを再帰的に訪問
    for(int next_v = 0; next_v < Graph[v].size();next_v++) {
        if(seen[Graph[v][next_v]] != -1) continue;
        dfs(Graph, Graph[v][next_v]);
    }
    // 出るときの時間が増える
    timestamp++;
    done[v] = timestamp; // 隣接ノードを全て調べ終えた
}

queue<int> que;
vector<long> dist;
// v: 何番目の頂点を訪問しているのか
void bfd(vector<vector<int> > &Graph, int v){
    done[v] = timestamp;

    for(int next_v = 0; next_v < Graph[v].size();next_v++){
        if(seen[Graph[v][next_v]] == -1){
            dist[Graph[v][next_v]] = dist[v] + 1;
            seen[Graph[v][next_v]] = timestamp;
            que.push(Graph[v][next_v]);
        }else{
            dist[Graph[v][next_v]] = min(dist[Graph[v][next_v]], dist[v] + 1);
        }
    }
}

#define TST 0
int main() {
#if TST==1
    ifstream in ("input.txt");
    cin.rdbuf(in.rdbuf());
#endif
    int n;
    cin >> n;
    vvi Graph;
    Graph.resize(n);
    F(i, 0, n){
        int id;
        cin >> id;
        int k;
        cin >> k;
        vi tmp;
        tmp.resize(k);
        F(j, 0, k){
           cin >> tmp[j]; 
           tmp[j]--;
        }
        Graph[i] = tmp;
    }
    seen.assign(n, -1);
    done.assign(n, -1);
    dist.assign(n, -1);
    que.push(0);
    seen[0] = 0;
    dist[0] = 0;
    while(!que.empty()){
       timestamp++;
       int front = que.front();
       bfd(Graph, front);
       que.pop();
    }

    F(i, 0, n){
        cout << i+1 << space << dist[i] << endl;;
    }

#if TST==1
#endif
}

C++: #include <bits/stdc++.h>
using namespace std;

#define INFTY 100000

void bfs(int s, vector<vector<int>> &M) {
    int n = M.size();
    queue<int> q;
    q.push(s);

    int d[n];
    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 << " ";
        if (d[i] == INFTY)
            cout << -1;
        else
        {
            cout << d[i];
        }
        cout << endl;
    }
}

int main() {
    int n;
    cin >> n;

    vector<vector<int>> M(n, vector<int>(n, 0));
    int u, k, v;
    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, M);
}