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 <queue>
#include <map>
#include <cstdio>
using namespace std;
main(){
	int t=0,T,i,j,k;
	map<int,vector<int> >a;
	for(scanf("%d",&T);t<T;t++)for(scanf("%d%d",&i,&k);k--;a[i].push_back(j))scanf("%d",&j);
	map<int,int>m;
	queue<int>q;
	for(q.push(1),m[1]=1;!q.empty();){
		k=q.front();q.pop();
		for(i=0;i<a[k].size();i++)if(!m[a[k][i]])m[a[k][i]]=m[k]+1,q.push(a[k][i]);
	}
	for(i=1;i<=T;i++)printf("%d %d\n",i,m[i]-1);
}

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

using namespace std;
int main(){
  int u, i, id, k, j;
  cin >> u;
  unordered_map<int, vector<int> > mymap;
  queue<vector<int> > myqueue;
  for (i = 0; i < u; ++i){
    cin >> id >> k;
    vector<int> points;
    for (j = 0; j < k; ++j){
      int a;
      cin >> a;
      points.push_back(a);
    }
    mymap[id] = points;
    if(id == 1){
      myqueue.push(points);
    }
  }
  
  bool visited[u+1];
  for (j = 1; j <= u; ++j){
    visited[j] = false;
  }
  visited[1] = true;

  int dist[u+1];
  for (j = 1; j <= u; ++j){
    dist[j] = -1;
  }
  dist[1] = 0;
  int d = 1;

  while(!myqueue.empty()){
    vector<int> combined;
    for (i = 0; i < myqueue.front().size(); ++i){
      if(!visited[myqueue.front()[i]]){
        dist[myqueue.front()[i]] = d;
        visited[myqueue.front()[i]] = true;
        if(combined.empty()){
          combined = mymap[myqueue.front()[i]];
        }else{
          combined.insert(combined.end(), mymap[myqueue.front()[i]].begin(), mymap[myqueue.front()[i]].end());
        }
      }
    }
    if(!combined.empty()){
      myqueue.push(combined);
    }
    myqueue.pop();
    d++;
  }

  for (j = 1; j <= u; ++j){
    cout << j << " " << dist[j] << endl;
  }

}

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

#define ll long long
#define vvi vector<vector<int>>
#define vec vector
#define pq priority_queue
#define all(v) (v).begin(), (v).end()
#define uniqueV(x) sort(x.begin(), x.end()); x.erase(unique(x.begin(), x.end()), x.end());
#define rep(i, n) for (int (i) = (0); (i) < (n); ++(i))
#define repp(i, m, n) for (int (i) = (m); (i) < (n); ++(i))
#define debug(x) cerr << #x << ": " << x << endl;
#define debug2(x, y) cerr<<"("<<#x<<", "<<#y<<") = "<<"("<<x<<", "<<y<<")"<<endl;
#define debug3(x, y, z) cerr<<"("<<#x<<", "<<#y<<", "<<#z<<") = "<<"("<<x<<", "<<y<<", "<<z<<")"<<endl;
#define debugB(x, y) cerr<<#x<<": "<<bitset<y>(x) << endl;
#define line() cerr << "---------------" << endl;

const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, -1, 1};

template<typename T>
void printA(vector<T> &printArray, char between = ' ') {
   int paSize = printArray.size();
   for (int i = 0; i < paSize; i++) { cerr << printArray[i] << between;}
   if (between != '\n') {cerr << endl;}
}

// ------------------------------------------------------------------------------------------

int N;
int dist[111];
vector<vector<int>> G;

int main() {
   cin >> N;
   G = vector<vector<int>>(N);
   rep (i, N) {
      int u, k; cin >> u >> k; u--;
      rep (i, k) {
         int a; cin >> a; a--;
         G[u].push_back(a);
      }
   }

   rep (i, N) dist[i] = -1;

   queue<int> que;
   que.push(0);
   dist[0] = 0;
   while (que.size()) {
      int cur = que.front(); que.pop();
      for (int x : G[cur]) {
         if (dist[x] == -1) {
            dist[x] = dist[cur] + 1;
            que.push(x);
         }
      }
   }

   rep (i, N) {
      printf("%d %d\n", i+1, dist[i]);
   }


   return 0;
}

C++: #if 0

#endif

#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;

int N;
int GM[110][110];

int D[110];
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 = 1; dst <= N; dst++) {
      if (GM[cur][dst] == 1 && !(D[dst] > 0)) {
        D[dst] = D[cur] + 1;
        Q.push(dst);
      }
    }
  }
}

int main() {
  cin >> N;
  for (int i = 1; i <= N; i++) {
    for (int j = 1; j <= N; j++)
      GM[i][j] = 0;
  }
  int u, k;
  for (int i = 1; i <= N; i++) {
    cin >> u >> k;
    int t;
    for (int j = 0; j < k; j++) {
      cin >> t;
      GM[i][t] = 1;
    }
  }
  bfs(1);
  cout << "1 0" << endl;
  for (int i = 2; i <= N; i++) {
    cout << i << ' ' << (D[i] > 0 ? D[i] : -1) << endl;
  }
}

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

using namespace std;

int main(){
	int n, u, k, v;
	int D[100];
	bool adj[100][100] = {};
	int pushed[100];
	cin >> n;
	for (int i = 0; i < n; i++){
		cin >> u >> k;
		for (int j = 0; j < k; j++){
			cin >> v;
			adj[u-1][v-1] = true;
		}
	}
	for (int i = 0; i < n; i++){
		D[i] = -1;
	}
	queue<int> Q;
	Q.push(1);
	D[0] = 0;
	pushed[0] = 1;
	while(!Q.empty()){
		int m = Q.front();
		Q.pop();
		for (int i = 0; i < n; i++){
			if (adj[m-1][i] == 1 && pushed[i] == 0){
				D[i] = D[m-1]+1;
				Q.push(i);
				pushed[i] = 1;
			}
		}
	}
	
	for (int i = 0; i < n; i++){
		cout << i+1 << ' ' << D[i] << endl;
	}
}