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 <iomanip>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <algorithm>
#include <cstdio>
#include <utility>
#include <string>
#include <cmath>
#include <cstdlib>
#include <cstring>

using namespace std;

typedef uint64_t u64;
typedef int64_t s64;
typedef uint32_t u32;
typedef int32_t s32;
typedef vector<s32> vs32;
typedef vector<u32> vu32;
typedef vector<s64> vs64;
typedef vector<u64> vu64;

const double PI=3.14159265358979323846;

#define MAX(x, y) ((x) < (y) ? (y) : (x))
#define MIN(x, y) ((x) > (y) ? (y) : (x))

#define rep(i, N) for(int i = 0; i < N; ++i)

#define CEIL(x, y) (((x) + (y) - 1) / (y))
#define MOD 1000000007ULL

class DirectedGraph
{
public:
    DirectedGraph() {}
    DirectedGraph(int n)
    : g(vector< vs32 >(n)), dist(vs32(n, -1))
    {}
    ~DirectedGraph() {}

    void bfs(int u)
    {
        int d = 0;
        dist[u]  = 0;
        queue<int> q;
        q.push(u);
        while (!q.empty())
        {
            int n = q.size();
            ++d;
            rep (i, n)
            {
                int v = q.front();
                q.pop();
                rep (j, g[v].size())
                {
                    if (dist[g[v][j]] < 0)
                    {
                        dist[g[v][j]] = d;
                        q.push(g[v][j]);
                    }
                }
            }
        }
    }

    vector< vs32 > g;
    vs32 dist;
};

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

    int n;
    cin >> n;

    DirectedGraph dg(n);
    int u, v;
    int c;
    rep (i, n)
    {
        cin >> u >> c;
        --u;
        dg.g[u].resize(c);
        rep (j, c)
        {
            cin >> v;
            --v;
            dg.g[u][j] = v;
        }
    }

    dg.bfs(0);

    rep (i, n)
    {
        cout << i + 1 << " " << dg.dist[i] << "\n";
    }
    return 0;
}

C++: #include <cstdio>
#include <queue>
using namespace std;
#define MAX_N 100

int g[MAX_N+1][MAX_N+1];
int d[MAX_N+1];
bool visited[MAX_N+1];
queue<int> que;

int n;
int t = 1;

void bfs(int id) {
  visited[id] = true;
  que.push(id);
  while(!que.empty()) {
    int v = que.front(); que.pop();
    queue<int> next_que;
    for(int u=1;u<=n;u++) {
      if(g[v][u]!=0 && !visited[u]) {
        visited[u]=true;
        next_que.push(u);
        d[u] = t;
      }
    }
    if(que.empty()){
      que = next_que;
      t++;
    }
  }
}

int main() {
  scanf("%d\n",&n);
  int u,k,v;
  for(int i=0;i<n;i++) {
    scanf("%d %d ",&u,&k);
    for(int j=0;j<k;j++) {
      scanf("%d ",&v);
      g[u][v] = 1;
    }
  }
  bfs(1);
  for(int i=1;i<=n;i++) {
    if(visited[i])
      printf("%d %d\n",i,d[i]);
    else
      printf("%d -1\n",i);
  }
}

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

void BFS(int s, const vector<vector<int> >& G, vector<int>& D){
    queue<int> Q;
    Q.push(s);
    D[s] = 0;
    while (!Q.empty()) {
        int f = Q.front();
        for (int i = 0; i < G[f].size(); i++) {
            if (D[G[f][i]] == -1) {
                D[G[f][i]] = D[f] + 1;
                Q.push(G[f][i]);
            }
        }
        Q.pop();
    }
}

int main(){
    int n;
    cin >> n;
    vector<vector<int> > G(n + 1);
    for (int i = 0; i < n; i++) {
        int u, k;
        cin >> u >> k;
        for (int j = 0; j < k; j++) {
            int v;
            cin >> v;
            G[u].push_back(v);
        }
    }
    vector<int> D(n + 1, -1);
    BFS(1, G, D);
    for (int i = 1; i <= n; i++) {
        cout << i << " " << D[i] << endl;
    }
    return 0;
}