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 <stdio.h>
#include <stdint.h>
#include <iostream>
#include <fstream>
#include <cassert>
#include <climits>

#include <memory>
#include <vector>
#include <queue>
using namespace std;

#define DEBUG (0)

#if DEBUG
#define DPRINTF(...) do { \
    printf("D(L%d) %s: ", __LINE__, __func__); \
    printf(__VA_ARGS__); \
  } while (false)
#else
#define DPRINTF(...)
#endif // DEBUG


struct Vertex {
  Vertex() :
    id_(-1),
    visited_(0),
    distance_(-1),
    adjNum_(-1) { }

  int id_;
  bool visited_;
  int distance_;
  int adjNum_;
  unique_ptr<int[]> adjIds_;

  void set(int id, vector<int> ids);
  void printInfo();
  void printDistance();
};


void Vertex::set(int id, vector<int> ids)
{
  id_ = id;
  adjNum_ = ids.size();

  if (adjNum_ == 0)
    return;

  adjIds_ = unique_ptr<int[]>(new int[adjNum_]);

  for (int i = 0; i < adjNum_; i++)
    adjIds_[i] = ids[i];
}


void Vertex::printInfo()
{
  DPRINTF("%d %d", id_, adjNum_);
  for (int i = 0; i < adjNum_; i++)
    printf(" %d", adjIds_[i]);
  cout << endl;
}


void Vertex::printDistance()
{
  printf("%d %d\n", id_, distance_);
}


void bfs(Vertex vertices[])
{
  const int startId = 1;
  queue<int> idQueue;

  idQueue.push(startId);

  int distance = 0;

  while (!idQueue.empty()) {

    DPRINTF("queue size %lu\n", idQueue.size());

    const size_t numOfThisDist = idQueue.size();

    for (size_t i = 0; i < numOfThisDist; i++)
    {
      int id = idQueue.front();
      idQueue.pop();

      DPRINTF("%zu  id %d\n", i, id);

      Vertex &vtx = vertices[id];

      if (vtx.visited_)
        continue;

      vtx.visited_ = true;
      vtx.distance_ = distance;

      for (int j = 0; j < vtx.adjNum_; j++)
        idQueue.push(vtx.adjIds_[j]);

    }

    distance++;
  }
}


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

  DPRINTF("%d\n", n);

  // do not use [0], it's empty
  Vertex vertices[n+1];

  for (int i = 1; i <= n; i++)
  {
    int node, adjNum;

    cin >> node >> adjNum;

    vector<int> adjs;

    for (int j = 0; j < adjNum; j++)
    {
      int v;
      cin >> v;
      adjs.push_back(v);
    }

    vertices[i].set(node, adjs);

    cin.ignore();

  }

#if DEBUG
  for (int i = 1; i <= n; i++)
    vertices[i].printInfo();
#endif // DEBUG

  bfs(vertices);

  for (int i = 1; i <= n; i++)
    vertices[i].printDistance();

  return 0;

}

C++: #define scanf_s scanf
#include <string>
#include <stdio.h>
#include <math.h>
#include <stack>
#include <queue>
#include <list>
#include <vector>
#include <iostream>
using namespace std;

#define MAX 100
//#define MAX_ 1000
struct Graph
{
	int id, k;
	list<int> node;
	int d = -1;
};
Graph G[MAX];
//int cou = 0;
void Breadth_cou(Graph *g,int cou)
{
	for (auto i = g->node.begin(); i != g->node.end(); ++i) {
		if (G[*i].d == -1 || G[*i].d > cou) {
			if (G[*i].d != -1) {
				Breadth_cou(&G[*i], cou + 1);
			}
			G[*i].d = cou;
		}
	}
}
void Breadth(Graph *g)
{
	if (g->k > 0) {
		Breadth_cou(g, g->d + 1);
		g->k = 0;
		for (auto i = g->node.begin(); i != g->node.end(); ++i) {
			Breadth(&G[*i]);
		}
	}
}
int main(void)
{
	int u, xk, v, n;
	scanf_s("%d", &n);
	for (int i = 0; i < n; ++i) {
		scanf_s("%d %d", &u, &xk);
		G[u - 1].id = u - 1;
		G[u - 1].k = xk;
		for (int j = 0; j < xk; ++j) {
			scanf_s("%d", &v);
			G[u - 1].node.push_back(v - 1);
		}
	}
	G[0].d = 0;
	Breadth(&G[0]);
	for (int i = 0; i < n; ++i) {
		printf("%d %d\n", G[i].id + 1, G[i].d);
	}
}

C++: #define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using graph = vector<vector<ll>>;
graph g;
ll n;
int main(){
    cin >> n;
    g.resize(n);
    for (ll i = 0; i < n; i++) {
        ll u, k; cin >> u >> k;
        for (ll j = 0; j < k; j++) {
            ll x; cin >> x;
            g[i].push_back(x-1);
        }
    }

    vector<ll> dist(n, -1);
    queue<ll> que;
    dist[0] = 0, que.push(0);
    while(!que.empty()){
        ll v = que.front(); que.pop();
        for(ll nv : g[v]){
            if(dist[nv] == -1){
                dist[nv] = dist[v] + 1;
                que.push(nv);
            }
        }
    }
    for (ll i = 0; i < n; i++)  printf("%lld %lld\n", i+1, dist[i]);
        
    return 0;
}

C++: #include<iostream>
#include<queue>
using namespace std;
int n,u,k,v,**M;

void bfs(int src)
{
  int D[100];
  for(int i=0;i<100;i++)
    D[i]=-1;
  queue<int>Q;
  Q.push(src);
  D[src]=0;
  while(!Q.empty())
    {
      int cur=Q.front();
      Q.pop();
     // cout<<cur+1<<' '<<D[cur]<<endl;
       for(int dst=0;dst<n;dst++)
	{
	  if(M[cur][dst]==1&&D[dst]==-1)
	    {
	      D[dst]=D[cur]+1;
	      Q.push(dst);
	    }
    }
    }
    for(int i=0;i<n;i++)
        cout<<i+1<<' '<<D[i]<<endl;
}

int main()
{
  //int n,u,k,v,**M;
  cin>>n;
  M=new int*[n];
  for(int i=0;i<n;i++)
    {
      M[i]=new int[n];
      for(int j=0;j<n;j++)
	M[i][j]=0;
    }
  int count=0;
  while(count<n)
    {
      count++;
      cin>>u>>k;
      for(int i=0;i<k;i++)
	{
	  cin>>v;
	  M[u-1][v-1]=1;
	}
    }
    bfs(0);
  delete M;
}