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 <vector>
#include <numeric>
#include <queue>

using namespace std;

int main() {
    int32_t n;
    cin >> n;

    vector<vector<int32_t>> A(n+1);

    for (int32_t i = 0; i < n; i++) {
        int32_t u, k;
        cin >> u >> k;

        for (int32_t j = 0; j < k; j++) {
            int32_t v;
            cin >> v;

            A[u].push_back(v);
        }
    }

    vector<bool> visited(n+1);
    fill(visited.begin(), visited.end(), false);
    vector<int32_t> d(n+1);
    fill(d.begin(), d.end(), -1);
    queue<int32_t> tovisit;
    visited[1] = true;
    d[1] = 0;
    tovisit.push(1);

    while (!tovisit.empty()) {
        int32_t u = tovisit.front();
        tovisit.pop();

        for (int32_t v : A[u]) {
            if (!visited[v]) {
                visited[v] = true;
                d[v] = d[u] + 1;
                tovisit.push(v);
            }
        }
    }

    for (int32_t i = 1; i <= n; i++) {
        cout << i << " " << d[i] << endl;
    }

    return 0;
}

C++: //INCLUDE
//------------------------------------------
#include <bits/stdc++.h>
//DEFINE
//------------------------------------------
#define ll long long
#define ld long double
#define ALLv(a)  (a).begin(),(a).end()
#define ALL(a,n)  (a),(a)+n
#define vi vector<long long>
#define vd vector<long double>
#define vs vector<string>
#define dcml(n) fixed<<setprecision(n)
//CONST
//------------------------------------------
const ll INF=1010000000000000017LL;
const ll MOD=1000000007LL;
const ld EPS=1e-12;
const ld PI=3.14159265358979323846;
//REPEAT
//------------------------------------------
#define   FOR(i,m,n) for(ll (i)=(m);   (i)<(n);  (i)++)
#define  FORS(i,m,n) for(ll (i)=(m);   (i)<=(n); (i)++)
#define  RFOR(i,m,n) for(ll (i)=(n)-1; (i)>=(n); (i)--)
#define RFORS(i,m,n) for(ll (i)=(n);   (i)>(n);  (i)--)
#define   REP(i,n)   for(ll (i)=0;     (i)<(n);  (i)++)
#define  REPS(i,x)   for(ll (i)=1;     (i)<=(x); (i)++)
#define  RREP(i,x)   for(ll (i)=(x)-1; (i)>=0;   (i)--)
#define RREPS(i,x)   for(ll (i)=(x);   (i)> 0;   (i)--)
#define  WREP(i,in,j,jn) REP(i,in)REP(j,jn)
#define WREPS(i,in,j,jn) REPS(i,in)REPS(j,jn)
//-----------------------------------------
//namespace
using namespace std;
//ライブラリはここに
//↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓

//-----------------------------------------
struct Edge{
    ll to;
};
vector<Edge> G[100];
ll N,d[100];
typedef pair<ll,ll> P;
void bfs(ll i){
    REP(i,N)d[i]=-1;
    queue<P> que;
    que.push(make_pair(0ll,0ll));
    d[0]=0;
    while(!que.empty()){
        P q=que.front();que.pop();
        //cout<<q.first+1<<":";
        for(auto r:G[q.first]){
            if(d[r.to]!=-1){
                //cout<<"continue";
                continue;
            }
            d[r.to]=q.second+1;
            //cout<<r.to+1<<" ";
            que.push(make_pair(r.to,q.second+1));
        }//cout<<"\n";
    }
}
int main(void){
    cin>>N;
    REP(i,N){
        ll idx,k;cin>>idx>>k;
        REP(j,k){
            ll to;cin>>to;to--;
            G[i].push_back({to});
        }
    }
    bfs(0);
    REP(i,N){
        cout<<i+1<<" "<<d[i]<<"\n";
    }
}

C++: #include <iostream>
#include <queue>
using namespace std;
static const int N = 101;
void bfs(int);
int n,M[N][N],d[N],u,i,j;
string color[N];
int main(){
  int inu,k,v;
  cin >> n;
  for(i=1;i<=n;i++){
    for(j=1;j<=n;j++){
      M[i][j]=0;
    }
  }
  for(i=1;i<=n;i++){
    cin >> inu >> k;
    for(j=0;j<k;j++){
      cin >> v;
      M[inu][v]=1;
    }
  }
  bfs(1);
  for(i=1;i<=n;i++){
    if(d[i]>1000000) cout << i << ' ' << -1 << endl;
    else cout << i << ' ' << d[i] << endl;
  }
  return 0;
}
void bfs(int s){
  queue<int> q;
  for(i=1;i<=n;i++){
    color[i]="WHITE";
    d[i]=1000000000;
  }
  color[s]="GLAY";
  d[s]=0;
  q.push(s);
  while(q.empty()!=true){
    u=q.front();
    q.pop();
    for(i=1;i<=n;i++){
      if(M[u][i]&&color[i]=="WHITE"){
	color[i]="GLAY";
	d[i]=d[u]+1;
	q.push(i);
      }
    }
    color[u]="BLACK";
  }
}

C++: #include <iostream>
#include <queue>
using namespace std;
static const int N = 1000;
static const int INFTY = (1 << 21);

int n, M[N][N];
int d[N];

void bfs(int s) {
	queue<int> q;
	q.push(s);
	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]) continue;
			if (d[v] != INFTY) continue;
			d[v] = d[u] + 1;
			q.push(v);
		}
	}
	for (int i = 0; i < n; ++i) {
		cout << i + 1 << " " << ((d[i] == INFTY) ? (-1) : d[i]) << endl;
	}
}

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

	cin >> n;
	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < n; ++j) M[i][j] = 0;
	}

	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);
}