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 <iostream>
using namespace std;

class Adjl{
private:
	int u;
	int k;
	Adjl **next;
public:
	Adjl(int u);
	~Adjl(){ if (next != NULL) delete[] next; }
	void setV(int k, Adjl *vk);
	int breadthFirstSearch(int id);
	void print(int id);
};

Adjl::Adjl(int u)
{
	this->u = u;
	k = 0;
	next = NULL;
}

void Adjl::setV(int k, Adjl *vk)
{
	if (this->k == 0) next = new Adjl*[k];
	next[this->k] = vk;
	(this->k)++;
}

int Adjl::breadthFirstSearch(int id)
{
	if (id == u) return 0;
	int d_min = -1;
	for (int i = 0; i < k; i++) {
		int d = next[i]->breadthFirstSearch(id);
		if (d == -1) continue;
		if (d_min == -1) d_min = d + 1;
		else d_min = min(d + 1, d_min);
	}
	return d_min;
}

void Adjl::print(int id)
{
	cout << id << " " << breadthFirstSearch(id) << endl;
}

int main(void)
{
	int n;
	cin >> n;
	
	Adjl **adjl = new Adjl*[n];
	int check[100] = {0};

	for (int i = 0; i < n; i++) {
		int u, k;
		cin >> u >> k;
		if (check[i] == 0) {
			adjl[i] = new Adjl(u);
			check[i] = 1;
		}
		check[i] = 1;
		for (int j = 0; j < k; j++) {
			int vk;
			cin >> vk;
			if (check[vk - 1] == 0) {
				adjl[vk - 1] = new Adjl(vk);
				check[vk - 1] = 1;
			}
			adjl[i]->setV(k, adjl[vk - 1]);
		}
	}

	for (int i = 1; i <= n; i++) {
		adjl[0]->print(i);
	}

	delete[] adjl;
	return 0;
}

C++: #define _USE_MATH_DEFINES
#include "bits/stdc++.h"
using namespace std;

//#define int long long
#define DBG 1
#define dump(o) if(DBG){cerr<<#o<<" "<<o<<endl;}
#define dumpc(o) if(DBG){cerr<<#o; for(auto &e:(o))cerr<<" "<<e;cerr<<endl;}
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define each(it,c) for(auto it=(c).begin();it!=(c).end();it++)
#define all(c) c.begin(),c.end()
const int INF = sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)(1e9 + 7);
vector<vector<int> >vec;
int n;
vector<int>d;
void bfs(int s) {
	queue<int>q;
	q.push(s);
	d[s] = 0;
	while (!q.empty()) {
		int u = q.front(); q.pop();
		rep(v, 0, vec[u].size()) {
			if (d[vec[u][v]] != INF)continue;
			d[vec[u][v]] = d[u] + 1;
			q.push(vec[u][v]);
		}
	}
	rep(i, 0, n) {
		cout << i + 1 << " " << d[i] << endl;
	}
}
signed main() {
	cin >> n; vec = vector<vector<int> >(n); d = vector<int>(n, INF);
	rep(i, 0, n) {
		int u, k; cin >> u >> k; u--;
		rep(j, 0, k) {
			int v; cin >> v; v--;
			vec[u].push_back(v);
		}
	}
	bfs(0);

	return 0;
}

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

int main(){
	int n;
	cin >> n;
	vector<int> G(n,-1);
	vector<vector<int>> vs(n);
	int u,k,v;
	for(int loop=0;loop<n;loop++){
		cin >> u >> k;
		for(int loop2=0;loop2<k;loop2++){
			cin >> v;
			vs[u-1].push_back(v-1);
		}
	}
	queue<pair<int,int>> Q;
	Q.push(make_pair(0,0));
	G[0]=0;
	int lk,dist;
	while(!Q.empty()){
		lk = Q.front().first;
		dist = Q.front().second;
		Q.pop();
		for(int loop=0;loop<vs[lk].size();loop++){
			if(G[vs[lk][loop]]==-1){
				G[vs[lk][loop]]=dist+1;
				Q.push(make_pair(vs[lk][loop],dist+1));
			}
		}
	}
	for(int loop=0;loop<n;loop++){
		cout << loop+1 << " " << G[loop] << endl;
	}
	return 0;
}

C++: #include <iostream>
using namespace std;
int n,g[100][100],f[100],c1[100],c2[100];
void bfs(int now,int far){
  for(int i=0;i<n;i++) if(g[now][i]){
      if(f[i]<far+1){
        c1[i]=1;
        continue;
      }
      f[i]=far+1;
    }
  for(int i=0;i<n;i++) if(g[now][i]&&c1[i]!=1) bfs(i,far+1);
}
int main(){

  int a,b,tmp;
  cin>>n;
  for(int i=0;i<n;i++){
    if(i) f[i]=1000;
    cin>>a>>b;
    for(int j=0;j<b;j++){
      cin>>tmp;
      g[a-1][tmp-1]=1;
    }
  }

  bfs(0,0);

  for(int i=0;i<n;i++) if(f[i]==1000) f[i]=-1;
  for(int i=0;i<n;i++) cout<<i+1<<" "<<f[i]<<endl;

  return 0;

}

C++: #include <iostream>
#include <set>
#include <vector>
#include <queue>
#include <stack>
#include <utility>

using namespace std;

typedef long long signed int ll;

constexpr ll NIL = -20000000000;

int g[101][101],n,d[101];

int main() {
    for(int i = 0;i < 101;i++)d[i] = -1;
    cin >> n;
    for(int i = 0;i < n;i++) {
        int u,k,v;
        cin >> u >> k;
        for(int j = 0;j < k;j++) {
            cin >> v;
            g[u][v]++;
        }
    }
    queue<int> q;
    q.push(1);
    d[1] = 0;
    while(!q.empty()) {
        int u = q.front();q.pop();
        for(int i = 1;i <= n;i++) {
            if(g[u][i] && d[i] == -1)
            {
                d[i] = d[u]+1;
                q.push(i);
            }
        }
    }
    for(int i = 1;i <=n;i++) {
        cout << i << " " << d[i] <<endl;
    }
}