Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

func stringifyArray(arr []int) string {
	return strings.TrimRight(fmt.Sprintf("%+v", arr)[1:], "]")
}

var infty = 1000000000

type nodeKey int

type DirectedGraphNode struct {
	key       nodeKey
	adjacents []*DirectedGraphNode
	visited   bool
	d         int
	parent    *DirectedGraphNode
}

type DirectedGraph struct {
	nodes []DirectedGraphNode
}

func (g *DirectedGraph) setAdjacency(l, r nodeKey) {
	g.nodes[l].adjacents = append(g.nodes[l].adjacents, &g.nodes[r])
}

func newDirectedGraph(nNodes int) *DirectedGraph {
	graph := DirectedGraph{}
	graph.nodes = make([]DirectedGraphNode, nNodes)
	for iNodes := 0; iNodes < nNodes; iNodes++ {
		graph.nodes[iNodes].key = nodeKey(iNodes)

		graph.nodes[iNodes].visited = false
		graph.nodes[iNodes].d = infty
		graph.nodes[iNodes].parent = nil
	}
	return &graph
}

type QueueEntry struct {
	node *DirectedGraphNode
	next *QueueEntry
}

type Queue struct {
	head, tail *QueueEntry
}

func (q *Queue) enqueue(node *DirectedGraphNode) {
	entry := QueueEntry{}
	entry.node = node

	if q.tail == nil {
		q.head = &entry
		q.tail = &entry
		return
	}

	q.tail.next = &entry
	q.tail = q.tail.next
}

func (q *Queue) dequeue() *QueueEntry {
	if q.head == nil {
		return nil
	}
	poped := q.head
	q.head = q.head.next
	if q.head == nil {
		q.tail = nil
	}
	return poped
}

func (q *Queue) isEmpty() bool {
	return q.head == nil
}

func fillDistancesByBreadthFirstSearch(g *DirectedGraph, startNode *DirectedGraphNode) {
	startNode.visited = true
	startNode.d = 0

	queue := Queue{}
	queue.enqueue(startNode)
	for !queue.isEmpty() {
		u := queue.dequeue().node
		for _, adjacent := range u.adjacents {
			if !adjacent.visited {
				adjacent.visited = true
				adjacent.d = u.d + 1
				adjacent.parent = u
				queue.enqueue(adjacent)
			}
		}
		u.visited = true
	}
}

func main() {
	scanner.Split(bufio.ScanWords)

	nNodes := nextInt()
	g := newDirectedGraph(nNodes + 1)

	for iNode := 0; iNode < nNodes; iNode++ {
		nodeKeyLeft := nodeKey(nextInt())
		nAdj := nextInt()
		for iAdj := 0; iAdj < nAdj; iAdj++ {
			nodeKeyRight := nodeKey(nextInt())
			g.setAdjacency(nodeKeyLeft, nodeKeyRight)
		}
	}

	// fmt.Println(g)
	fillDistancesByBreadthFirstSearch(g, &g.nodes[1])
	// fmt.Println(g)

	for iNode := 1; iNode <= nNodes; iNode++ {
		node := g.nodes[iNode]
		distance := node.d
		if distance == infty {
			distance = -1
		}
		fmt.Println(node.key, distance)
	}
}

C++: #include <iostream>
#include <vector>
#include <queue>
#define eol '\n'
using namespace std;

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);

  int n;
  cin >> n;
  
  queue<int> que;
  vector< vector<int> > list(n+1);
  vector<int> d(n+1, -1);

  for (int i = 0; i < n; i++) {
    int u,k;
    cin >> u >> k;
    
    vector<int> row(k);
    for (int j = 0; j < k; j++) {
      cin >> row[j];
    }
    list[u] = row;
  }

  d[1] = 0;
  que.push(1);
  while(que.size()) {
    int v = que.front();
    que.pop();

    int dis = d[v];

    for (int i = 0; i < list[v].size(); i++) {
      int next = list[v][i];
      if (d[next] == -1) {
        d[next] = dis+1;
        que.push(next);
      }
    }
  }

  for (int i = 1; i <= n; i++) {
    cout << i << " " << d[i] << eol;
  }
  
  return 0;
}

C++: #include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define repr(i, n) for (int i = (n); i >= 0; --i)
#define FOR(i, m, n) for (int i = (m); i < (n); ++i)
#define FORR(i, m, n) for (int i = (m); i >= (n); --i)
using namespace std;
typedef long long ll;
const ll mod = 1000000007;
const ll mod2 = 998244353;
const int N = 100;
const int INF = 1<<21;
int n, M[N][N];
int d[N];

void bfs(int s) {
  queue<int> q;
  q.push(s);
  rep(i, n) d[i] = INF;
  d[s] = 0;
  int u;
  while(!q.empty()) {
    u = q.front();
    q.pop();
    rep(v, n) {
      if (!M[u][v]) continue;
      if (d[v] != INF) continue;
      d[v] = d[u] + 1;
      q.push(v);
    }
  }
  rep(i, n) {
    cout << i+1 << " " << ((d[i] == INF) ? (-1) : d[i]) << endl;
  }
}

int main() {
  int u, k, v;
  cin >> n;
  rep(i, n) {
    rep(j, n) {
      M[i][j] = 0;
    }
  }
  rep(i, n) {
    cin >> u >> k;
    u--;
    rep(j, k) {
      cin >> v;
      v--;
      M[u][v] = 1;
    }
  }
  bfs(0);
  
  return 0;
}

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

typedef long long ll;


int d[200];
bool table[200][200];

void init(){
    for(int i=0;i<200;i++){
        d[i]=-1;
        for(int j=0;j<200;j++){
            table[i][j]=false;
        }
    }
}

void bfs(int itr, int dis, int n){
    d[itr] = dis;
    for(int i=0;i<n;i++){
        if(table[itr][i]&&(d[i]<0||d[i]>dis+1)){
            bfs(i, dis+1,n);
        }
    }
}

void solve(int n){
    bfs(0,0,n);
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);

    init();
    int n;
    cin >> n;
    int u,k,v;
    for(int i=0;i<n;i++){
        cin >> u >> k;
        for(int j=0;j<k;j++){
            cin >> v;
            table[u-1][v-1]=true;
        }
    }

    solve(n);

    for(int i=0;i<n;i++){
        cout << i+1 << " " << d[i] << endl;
    }

    return 0;
}

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

int main() {
	int a[101][101] = {{0}};
	int u, k, v, km;
	km = 0;
	while ( cin >> u, k ) {
		for ( int i = 1; i <= k; i++ ) {
			cin >> v;
			a[u][v] = 1;
		}
		km++;
	}
	int n0;
	int b[km + 1] = {- 1};
	queue<int> q;
	q.push( 1 );
	b[1] = 0;
	int cou = 0;
	for ( int i = 1; i <= km; i++ ) {
		n0 = q.front();
		q.pop();
		cou++;
		for ( int j = 1; j <= km + 1; j++ ) {
			if ( a[n0][j] == 1 && b[j] == - 1 ) {
				q.push( j );
				b[j] = cou;
			}
			if ( q.empty ) break;
		}
	}
	for ( int i = 1; i <= km; i++ )
		cout << i << " " << b[i] << endl;
}

C++: #include <bits/stdc++.h>
using namespace std;
int N,mas[101][101],v[101],cnt=0,st[101];
queue<int> q;

void bfs(int u){
    v[u]++;
    //st[u]=cnt;
    q.push(u);
    while(!q.empty()){
        int n=q.front();
        q.pop();
        for(int i=1;i<N+1;i++){
            if(mas[n][i] && !v[i]){
                v[i]++;
                st[i]=st[n]+1;
                q.push(i);
            }
        }
    }
}

int main(void){
    // Your code here!
    int u,k,vx;
    cin>>N;
    
    for(int i=1;i<N+1;i++){
        cin>>u>>k;
        for(int j=1;j<k+1;j++){
            cin>>vx;
            mas[u][vx]++;
        }
    }
    
    bfs(1);
    for(int i=1;i<N+1;i++){
        if(i>1&& !st[i]) cout<<i<<" "<<"-1"<<endl;       
        else cout<<i<<" "<<st[i]<<endl;  
    } 
}

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

static const int N=100;
static const int INFTY=(1<<21);

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

void dfs(int a){
  queue<int> q;
  q.push(a);
  for(int i=0;i<n;i++) d[i]=INFTY;
  d[a]=0;
  int b;
  while(!q.empty()){
    b=q.front();
    q.pop();
    for(int j=0;j<n;j++){
      if(m[b][j]==0) continue;
      if(d[j]!=INFTY) continue;
      d[j]=d[b]+1;
      q.push(j);
    }
  }
  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;
    }
  }
  dfs(0);
  return 0;
}