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;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }

using Lint=long long;
using Graph=vector<vector<int>>;

const int INF=1e9;

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

    int N; cin>>N;
    Graph G(N);
    for(int i=0;i<N;i++){
        int u,k; cin>>u>>k;
        u--;
        while(k--){
            int v; cin>>v;
            v--;
            G[u].push_back(v);
        }
    }

    vector<int> dist(N,INF);
    dist[0]=0;
    queue<int> Q;
    Q.push(0);
    while(!Q.empty()){
        int v=Q.front(); Q.pop();
        for(int u:G[v]){
            if(chmin(dist[u],dist[v]+1)) Q.push(u);
        }
    }
    for(int i=0;i<N;i++){
        cout<<i+1<<' '<<(dist[i]==INF? -1:dist[i])<<endl;
    }
    return 0;
}

C++: /*
    Problem 28
    https://onlinejudge.u-aizu.ac.jp/problems/ALDS1_11_C
*/
#include <bits/stdc++.h>
using namespace std;
/* typedef */
typedef long long ll;
typedef pair<int, int> pii;
/* constant */
const int INF = 1 << 30;
const ll LINF = 1LL << 50;
const int NIL = -1;
const int MAX = 105;
const int mod = 1000000007;
const double pi = 3.141592653589;
/* global variables */
vector<vector<int>> G(MAX, vector<int>(MAX));
vector<int> dist(MAX, -1);
/* function */
void bfs() {
    queue<int> q;
    q.push(0);
    dist[0] = 0;  // distで訪れたかどうかcheck
    while (!q.empty()) {
        int from = q.front();
        q.pop();
        for (int to : G[from]) {
            if (dist[to] != -1) continue;
            dist[to] = dist[from] + 1;
            q.push(to);
        }
    }
}
/* main */
int main(){
    int N;
    cin >> N;
    for (int i = 0; i < N; i++) {
        int u, k;
        cin >> u >> k;
        u--;
        for (int j = 0; j < k; j++) {
            int v;
            cin >> v;
            v--;
            // 有効グラフ
            G[u].push_back(v);
        }
    }

    bfs();

    for (int i = 0; i < N; i++) cout << i+1 << ' ' << dist[i] << '\n';
}

C++: #include <iostream>
#include <climits>
#include <vector>
#include <queue>
#define WHITE 0
#define GRAY 1
#define BLACK 2
#define INF INT_MAX

using namespace std;

void bfs(int s, int n, int *color, int *d, vector<vector<int>> Adj){
    queue<int> Q;
    for (int u = s+1; u <= n; u++){
        color[u] = WHITE;
        d[u] = INF;
    }
    color[s] = GRAY;
    d[s] = 0;
    Q.push(s);
    while (Q.size() != 0){
        int zero = 0;
        int u = Q.front();
        Q.pop();
        for (int w = 1; w < Adj[u].size(); w++){
            int v = Adj[u][w];
            if (v == 0){
                break;
            }else if (color[v] == WHITE){
                color[v] = GRAY;
                d[v] = d[u] + 1;
                Q.push(v);
                zero++;
            }
        }
        color[u] = BLACK;
    }
}

int main(int argc, char* argv[]) {
    int n, u, k, v;
    cin >> n;
    n++;
    int color[n], d[n], f[n];
    vector<vector<int>> Adj(n, vector<int>(n, 0));

    for (int i = 1; i < n; i++){
        cin >> u >> k;
        for (int j = 1; j <= k; j++){
            cin >> v;
            Adj[i][j] = v;
        }
    }

    bfs(1, n, color, d, Adj);

    for (int i = 1; i < n; i++){
        if (d[i] == INF)
            printf("%d -1\n", i);
        else
            printf("%d %d\n", i, d[i]);
    }
    return 0;
}

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

map<int, vector<int>> A;
int color[101];
int D[101];
int d = 0;

void dfs(int u) {
    queue<int> Q;
    Q.push(u);
    color[u] = 1;
    int current;
    D[u] = d;
    while(!Q.empty()) {
        current = Q.front();
        Q.pop();
        vector<int>::iterator it = A[current].begin();
        while(it != A[current].end()) {
            if (color[*it] == 0) {
                Q.push(*it);
                color[*it] = 1;
                D[*it] = D[current] + 1;
            }
            it++;
        }
    }
}

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

    int u, k;
    for (int i = 1; i <= n; i++) {
        color[i] = 0;
        D[i] = -1;
        cin >> u >> k;
        int ad;
        for (int j = 0; j < k; j++) {
            cin >> ad;
            A[u].push_back(ad);
        }
    }

    dfs(1);

    for (int i = 1; i <= n; i++) {
        cout << i << " " << D[i] << endl;
    }
}