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 <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;

int main()
{
  int n;
  cin >> n;
  Graph G(n + 1);
  int u, k, v;
  for (int i = 0; i < n; i++)
  {
    cin >> u >> k;
    for (int j = 0; j < k; j++)
    {
      cin >> v;
      G.at(u).push_back(v);
    }
  }
  vector<int> dist(n + 1, -1);
  queue<int> que;
  dist.at(1) = 0;
  que.push(1);
  int nv;
  while (!que.empty())
  {
    v = que.front();
    que.pop();
    for (int i = 0; i < G.at(v).size(); i++)
    {
      nv = G.at(v).at(i);
      if (dist.at(nv) != -1)
      {
        continue;
      }
      dist.at(nv) = dist.at(v) + 1;
      que.push(nv);
    }
  }
  for (int i = 1; i <= n; i++)
  {
    cout << i << " " << dist.at(i) << endl;
  }
}

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

using namespace std;

vector<int> G[100 + 5];
int d[105];
bool travel[105];

int main()
{
    cin.tie(0);
    cin.sync_with_stdio(0);
    int n;
    cin >> n;
    int u, k, now;
    for (int i = 1; i <= n; ++i) {
        cin >> u >> k;
        while (k--) {
            cin >> now;
            G[u].push_back(now);
        }
    }
    fill(d, d + 105, -1);
    queue<pair<int, int> > q;
    q.push({1, 0});
    while (!q.empty()) {
        int now = q.front().first;
        int distance = q.front().second;
        q.pop();
        if (travel[now]) continue;
        travel[now] = true;
        d[now] = distance;
        for (auto i : G[now]) {
            q.push({i, distance + 1});
        }
    }
    for (int i = 1; i <= n; ++i) {
        cout << i << ' ' << d[i] << '\n';
    }
}

C++: //push(),pop():C++ではstackと統一されいる
//front():先頭の要素が何かを返す
//back():末尾の要素が何であるかを返す
//empty():キューが空であるかどうかを調べる
//size():要素数を調べる
#include<stdio.h>
#include <iostream>
#include <queue>
using namespace std;
#define MAX 101
#define WHITE 0
#define GRAY 1
#define BLACK 2
static const int INFTY = (1<<21);

int G[MAX][MAX],color[MAX],d[MAX],num;

void bfs(int s){
  int u;
  queue<int> Q; //Qを使うことでエンキュー、デキューの操作が容易になる
  for(int i=1; i<=num; i++) {
    d[i] = INFTY;
  }
  Q.push(s);
  d[s] = 0;
  while(!Q.empty()){
    u = Q.front();
    Q.pop();
    for(int v=1; v<=num; v++){
      if(G[u][v] == 0) continue;
      if(d[v] != INFTY) continue;
      d[v] = d[u] + 1;
      Q.push(v);
    }
  }
}


int main(){
  int i,j,u,k,v;

  scanf("%d",&num);
  for(i=1; i<=num; i++){
    color[i] = WHITE;
    for(j=1; j<=num; j++){
      G[i][j] = 0;
    }
  }
  for(i=1; i<=num; i++){
    scanf("%d%d",&u,&k);
    for(j=1; j<=k; j++){
      scanf("%d",&v);
      G[u][v] = 1;
    }
  }

  bfs(1);

  for(i=1; i<=num; i++) {
    if(d[i] == INFTY) printf("%d -1\n",i);
    else printf("%d %d\n",i,d[i]);

  return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <queue>
#include <stack>
#include <map>
#define FOR(i,b,e) for(int i=b;i<e;i++)
#define REP(i,n) FOR(i,0,n)
using namespace std;

const int N = 100;
int n;
int d[N+1];
vector< vector<int> > ns;
queue<int> q;

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

  vector<int> v;
  ns.push_back(v);
  cin >> n;
  FOR(i, 1, n+1) {
    int id, k, x; cin >> id;
    vector<int> v;
    cin >> k;
    REP(j, k) {
      cin >> x;
      v.push_back(x);
    }
    ns.push_back(v);
  }

  FOR(i, 1, n+1) d[i] = -1;

  int u = 1;
  q.push(u);
  d[u] = 0;
  while (!q.empty()) {
    u = q.front();
    q.pop();
    REP(i, ns[u].size()) {
      int v = ns[u][i];
      q.push(v);
      if (d[v] == -1) d[v] = d[u] + 1;
    }
  }

  FOR(i, 1, n+1) {
    cout << i << " " << d[i] << endl;
  }
}