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 <queue>
using namespace std;

struct node
{
	int distance;
	bool accessed;
	node(int d, bool a) : distance(d), accessed(a) {}
};

void bfs(vector<node> &nodes, vector<vector<bool>> &conn_mat)
{ //index = n-1
	nodes[0].accessed = true;
	nodes[0].distance = 0;
	queue<int> bfs_queue;
	bfs_queue.push(0);
	int dis = 0;
	while (!bfs_queue.empty())
	{
		int index = bfs_queue.front();
		int i = 0;
		bfs_queue.pop();
		for (auto connected : conn_mat[index])
		{
			if (connected && (!nodes[i].accessed))
			{
				bfs_queue.push(i);
				nodes[i].accessed = true;
				nodes[i].distance = nodes[index].distance + 1;
			}
			i++;
		}
	}
}

int main()
{

	int n_node, index, n_cn, cn;
	cin >> n_node;
	vector<node> nodes(n_node, node(-1, false));
	vector<bool> vertex(n_node, false);
	vector<vector<bool>> conn_mat(n_node, vertex);
	while (n_node--)
	{
		cin >> index >> n_cn;
		while (n_cn--)
		{
			cin >> cn;
			conn_mat[index - 1][cn - 1] = true;
		}
	}
	bfs(nodes, conn_mat);
	int i = 0;
	for (node nd : nodes)
	{
		i++;
		cout << i << ' ' << nd.distance << endl;
	}
	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <string>
#include <stack>
#include <cstdlib>
#include <queue>
#include <vector>
#include <set>

using namespace std;
int n,m,l,p;
bool a[100][100];
int D[100];
void  bfs ( int src) {
	queue<int> Q;
	Q.push(src);
	D[src]=0;
	while( ! Q.empty() ) {
		int cur = Q.front();
		Q.pop();
		for(int dst = 0; dst < n; dst++ ) {
			if( D[dst] == 0 && a[cur][dst] == 1 ) {
				D[dst] = D[cur] + 1;
				Q.push(dst);
			}
		}
	}
	for (int i = 0; i < n;i++) {
	cerr << i+1 <<  " " << D[i] <<  endl;
	}
}
int main() {
	cin >> n;
	for (int i = 0;i < n; i++){
		cin >> m;
		cin >> l;
		for(int j = 0; j < l;j++) {
			a[i][j] = 0;
			cin >> p;
			a[m-1][p-1] = 1;
		}
	}
		bfs(0);
}

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

int n;
vector<int> G[110];
int d[110];

void bfs(){
  queue<int> que;
  for(int i=0; i<n; i++){
    d[i] = -1;
  }
  d[0] = 0;
  que.push(0);
  while(!que.empty()){
    int v = que.front(); que.pop();
    for(int i=0; i<G[v].size(); i++){
      int nv = G[v][i];
      if(d[nv] < 0){
        que.push(nv);
        d[nv] = d[v] + 1;
      }
    }
  }
}

int main(){
  cin >> n;
  for(int i=0; i<n; i++){
    int u, k; cin >> u >> k;
    for(int i=0; i<k; i++){
      int c; cin >> c;
      G[u-1].push_back(c-1);
    }
  }
  bfs();
  for(int i=0; i<n; i++){
    cout << i+1 << " " << d[i] << endl;
  }
}

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

int n;
char c[101];
int g[101][101];
int t = 0;
int visit[101];
int finish[101];
int d[101];
int dist = 0;

void bfs(int start) {
    t++;
    queue<int> q;
    q.push(start);
    c[start] = 'g';
    visit[start] = t;
    while(!q.empty()) {
        t ++;
        int now = q.front();
        dist ++;
        for (int i = 1; i <= n ; ++i) {
            if(g[now][i] && c[i] == 'w') {
                q.push(i);
                c[i] = 'g';
                visit[i] = t;
                d[i] = d[now] + 1;
            }
        }
        q.pop();
        c[now] = 'b';
        finish[now] = t;
    }
}
int main() {
    cin >> n;
    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][v] = 1;
        }
    }

    for (int l = 0; l < n; ++l) {
        c[l+1] = 'w';
    }

    for (int i1 = 1; i1 <=n ; ++i1) {
        d[i1] = -1;
    }
    for (int m = 1; m <= n ; ++m) {
        d[1] = 0;
        if(c[m] == 'w') bfs(m);
        break;

    }
    for (int j1 = 1; j1 <=n ; ++j1) {
        cout << j1 << " " << d[j1] << endl;
    }

    return 0;
}

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

using namespace std;
static const int N = 100;
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] == 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 << " " << ( (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);

  return 0;
}

C++: #include <iostream>
#include<queue>
using namespace std;
#define INF 9999999

int G[101][101];
int dis[101];
int main(){
  int n;
  cin>>n;
  for(int i=0;i<n;i++){
    int u,k;
    cin>>u>>k;
    for(int j=1;j<=k;j++){
      G[u][0]=k;
      cin>>G[u][j];
    }
  }
  fill(dis,dis+101,INF);
  dis[1]=0;
  queue<int> Q;
  Q.push(1);
  while(!Q.empty()){
    int num=Q.front(); Q.pop();
    for(int i=1;i<=G[num][0];i++){
      int k=G[num][i];
      dis[k]=min(dis[num]+1,dis[k]);
      Q.push(k);
    }
  }
  for(int i=1;i<=n;i++){
    cout<<i<<" "<<dis[i]<<"\n";
  }
}