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 <cstdio>
#include <cstring>
#include <vector>
#include <queue>
//original idea: stupid wanna check the node with many bfs search 
using namespace std;
#define N 105 // number of nodes
vector<int> neighbors[N]; //start from 1
queue<int> q;
//http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_11_C bfs
int dist[N];
int vis[N];
int res = 0;
void bfs(int d){
	if(q.empty()) return;
	//until q is empty
	while(!q.empty()){
		int temp = q.front();
		q.pop();
		if(dist[temp]!=-1){
			if(d<dist[temp]) dist[temp] = d;
			else {dist[temp] = dist[temp];}
		}else {
			dist[temp] = d;
		}
		for(int i = 0; i<neighbors[temp].size(); i++){
			d = dist[temp] +1;//next lever
		if(dist[neighbors[temp].at(i)] == -1){//not visited
			q.push(neighbors[temp].at(i));
			dist[neighbors[temp].at(i)] = d;
			}
		}
		
	}
	
}

int main()
{
    int n;
    scanf("%d",&n);
    memset(dist, -1, sizeof(dist));
    memset(vis, -1, sizeof(dist));
    for(int i = 0; i<n; i++){
        int node;
        scanf("%d",&node);
        int num;
        scanf("%d",&num);
        for(int j = 0; j<num; j++){
        	int temp;
        	scanf("%d",&temp);
        	neighbors[node].push_back(temp);
        	neighbors[temp].push_back(node);
		}
    }
	q.push(1);//begin from 1
    bfs(0);
    for(int i = 1; i<=n; i++){
    	printf("%d %d\n",i, dist[i]);
	}
    return 0;
}

C++: #include<iostream>
#include<queue>
#define INF 1000000
using namespace std;

 queue<int> q;
int a[101][101];
int d[101];
int n;

void bfs(int s){
  int t;
  for(int i=1;i<=n;i++)d[i]=INF;
  d[s]=0;
  while(!q.empty()){
    t=q.front(),q.pop();
    for(int i=1;i<=n;i++){
      if(d[i]!=INF || a[t][i]!=1) continue;
       q.push(i),d[i]=d[t]+1;
    }
  }
}

int main(){
  int top,m,s;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>top>>m;
    for(int j=0;j<m;j++)
      cin>>s,a[top][s]=1;
     } 
  q.push(1);
   bfs(1);
  for(int i=1;i<=n;i++) cout<<i<<" "<<d[i]<<endl;
    return 0;
}

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

using namespace std;

queue<int> que;

void bfs(vector<vector<int> > &G, int s, int *seen) {
    seen[s] = 0;
    que.push(s);
    
    while (!que.empty()) {
        int u = que.front();
        que.pop();

        for (int i = 0; i < G[u].size(); i++) {
            int v = G[u][i];

            if (seen[v] != -1)  
                continue;

            seen[v] = seen[u] + 1;
            que.push(v);
        }
    }
}

int main() {
    vector<vector<int> > G;
    int n;  cin >> n;
    G.resize(n);
    for (int i = 0; i < n; i++) {
        int u, k;   cin >> u >> k;
        for (int j = 0; j < k; j++) {
            int x;  cin >> x;
            G[u-1].push_back(x-1);
        }
    }

    int *seen = new int[n];
    for (int i = 0; i < n; i++)
        seen[i] = -1;
    seen[0] = 0;

    bfs(G, 0, seen);

    for (int i = 0; i < n; i++)
        cout << i+1 << " " << seen[i] << endl;

    return 0;
}

C++: #include<cstdio>
#include<queue>
using namespace std;
static const int INF=(1<<21);
static const int MAXN=101;
struct p{
	int d;
	int cnt;
};
int main()
{
	int n,m[MAXN][MAXN],i,j,u,k,v,l,t[MAXN];
	p e,f;
	queue<p> q;
	bool used[MAXN]={};
	scanf("%d",&n);
	for(i=1;i<n+1;i++){
		for(j=1;j<n+1;j++){
			m[i][j]=INF;
		}
	}
	for(i=0;i<n;i++){
		scanf("%d %d",&u,&k);
		for(j=0;j<k;j++){
			scanf("%d",&v);
			m[u][v]=1;
		}
	}
	used[1]=true;
	e.d=1;
	e.cnt=0;
	q.push(e);
	while(!q.empty()){
		e=q.front();
		q.pop();
		for(i=1;i<n+1;i++){
			if(m[e.d][i]==1&&used[i]==false){
				f.d=i;
				f.cnt=e.cnt+1;
				q.push(f);
				used[i]=true;
				t[i]=e.cnt+1;
			}
		}
	}
	for(i=1;i<n+1;i++){
		if(used[i]==true){
			printf("%d %d\n",i,t[i]);
		}
		else{
			printf("%d -1\n",i);
		}
	}
	return 0;
}

C++: #include<bits/stdc++.h>
#include<string>
#include<cctype>
#include<cmath>
#include<queue> 
#define rep(i,n) for(int i=0;i<(n);i++)
using namespace std;
 
int main(){
  queue <int> q1;
  int n,i,j;
  cin >> n;
  int d[n][n];
  int m[n];
  int v[n];
  rep(i,n){
    m[i]=10000;
    v[i]=0;
    rep(j,n){
      if(i==j){
        d[i][j]=0;
      }else{
        d[i][j]=10000;
      }
    }
  }
  m[0]=0;

  rep(i,n){
    int u,k;
    cin >> u >> k;
    if(k>0){
      rep(j,k){
        int v;
        cin >> v;
          d[u-1][v-1]=1;
      }
    }
  }   

  q1.push(0);
  while(!q1.empty()){
    int u = q1.front(); q1.pop();
      rep(j,n){
        if(d[u][j]==1 && v[j]==0){
          q1.push(j);
          m[j] = min(m[j],m[u]+1);
        }
      }
    v[u]=1;
  }

  rep(i,n){
    cout << i+1 << ' ';
    if(m[i]==10000){
      cout << -1 << endl;
    }else{
      cout << m[i] << endl;
    }
  }

  return 0;
}