Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

type AdjacentList struct {
	matrix [][]int
}

func NewEmptyAdjacentList(dim int) *AdjacentList {
	matrix := make([][]int, dim)
	for i := 0; i < dim; i++ {
		matrix[i] = make([]int, dim)
	}
	return &AdjacentList{matrix: matrix}
}

func (al *AdjacentList) set(node int, adjacent int) {
	al.matrix[node-1][adjacent-1] = 1
}

func (al *AdjacentList) findAdjacentsFor(node int) []int {
	adjacents := []int{}
	for i, v := range al.matrix[node-1] {
		if v == 1 {
			adjacents = append(adjacents, i+1)
		}
	}
	return adjacents
}

type DistanceList struct {
	list []int
}

func NewDistanceList(dim int) *DistanceList {
	list := make([]int, dim)
	for i := 0; i < dim; i++ {
		list[i] = -1
	}
	return &DistanceList{list: list}
}

func (dl *DistanceList) set(node int, distance int) {
	dl.list[node-1] = distance
}

func (dl *DistanceList) get(node int) int {
	return dl.list[node-1]
}

func (dl *DistanceList) isVisited(node int) bool {
	return dl.list[node-1] >= 0
}

type Position struct {
	node     int
	distance int
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	dim, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	al := NewEmptyAdjacentList(dim)

	for i := 1; i <= dim; i++ {
		node, err := nextInt(sc)
		if err != nil {
			panic(err)
		}

		adjacentNum, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		for j := 0; j < adjacentNum; j++ {
			adjacent, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			al.set(node, adjacent)
		}
	}

	dl := NewDistanceList(dim)

	bfs(al, dl)

	for i := 1; i <= dim; i++ {
		fmt.Printf("%d %d\n", i, dl.get(i))
	}
}

func bfs(al *AdjacentList, dl *DistanceList) {
	stack := []Position{Position{node: 1, distance: 0}}
	for len(stack) > 0 {
		currentPosition := stack[0]
		stack = stack[1:]
		if !dl.isVisited(currentPosition.node) {
			dl.set(currentPosition.node, currentPosition.distance)
		}
		for _, v := range al.findAdjacentsFor(currentPosition.node) {
			if !dl.isVisited(v) {
				stack = append(stack, Position{node: v, distance: currentPosition.distance + 1})
			}
		}
	}
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

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

#define FOR(i,k,n) for (int (i)=(k); (i)<(n); ++(i))
#define REP(i,n) FOR(i,0,n)
using namespace std;

int main(){
    int n,u,k,v,src=0;
    cin >> n;
    int D[n],g[n][n];
    REP(i,n){
        D[i] = -1;
        REP(j,n){
            g[i][j] = 0;
        }    
    }
    REP(i,n){ 
        cin >> u >> k;
            REP(j,k){
                cin >> v;
                g[u-1][v-1] = 1;
            }
    }

    queue<int> Q;
    Q.push(src);
    D[src] = 0;
    while (!Q.empty()) {
        int cur = Q.front();
        Q.pop();
            REP(i,n){
                if(g[cur][i] == 1 && D[i] < 0){
                    D[i] = D[cur] + 1;
                    Q.push(i);
                }
            }
    }

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

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

int n;
int u[101], k[101], d[101];
vector<vector<int>> g;
queue<pair<int, int>> q;

int main() {
	cin >> n;
	g.resize(n+1);
	for(int i=1;i<=n;i++){
		d[i] = -1;
		cin >> u[i] >> k[i];
		if(k[i]){
			for(int j=0;j<k[i];j++){
				int v; cin >> v;
				g[u[i]].push_back(v);
			}
		}
	}
	q.push({1,0});
	while(!q.empty()){
		int a = q.front().first;
		d[a] = q.front().second;
		q.pop();
		for(auto c: g[a]){
			if(d[c]!=-1) continue;
			else{
				d[c] = d[a]+1;
				q.push(make_pair(c, d[c]));
			}
		}
	}
	for(int i=1;i<=n;i++){
		cout << i << ' ' << d[i] << endl;
	}
	return 0;
}

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 <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
using namespace std;
using ll = long long;
using P = pair<int, int>;

vector<int> to[100];
int ans[100];

int main() {
  int n;
  cin >> n;
  rep(i, n) {
    int u, k;
    cin >> u >> k;
    vector<int> v(k);
    rep(j, k) {
      int vj;
      cin >> vj;
      vj--;
      v[j] = vj;
    }
    to[i] = v;
    ans[i] = -1;
  }

  queue<int> q;
  q.push(0);
  ans[0] = 0;
  while (!q.empty()) {
    int now = q.front();
    q.pop();
    for (int next : to[now]) {
      if (ans[next] != -1) continue;
      ans[next] = ans[now] + 1;
      q.push(next);
    }
  }

  rep(i, n) printf("%d %d\n", i + 1, ans[i]);

  return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <set>
#include <math.h>
using namespace std;
typedef long long int ll;
#define rep(i, a, n) for (ll i = a; i < (ll)(n); i++)
long long GCD(long long a, long long b) { return b ? GCD(b, a%b) : a; }
long long LCM(long long a, long long b)  {return a/GCD(a,b)*b;}
int n;
int graph[101][101];
int d[101];
int k[101];
bool beg[101];
int cnt=0;
int pre=-6;
queue<int>now;
queue<int>nextg;
int main(){
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        beg[i]=false;
        d[i]=-1;
        int number;
        cin>>number;
        cin>>k[i];
        for(int j=1;j<=k[i];j++)
        {  cin>>graph[i][j];
        }
    }
    for(int j=1;j<=k[1];j++)
    {  now.push(1);
        nextg.push(graph[1][j]);
    }
    d[1]=0;
    beg[1]=true;
    while(now.size())
    {
        int nowt=now.front();
        int nextt=nextg.front();
        
        now.pop();
        nextg.pop();
        if(beg[nextt]==false)
        {
            d[nextt]=d[nowt]+1;
            beg[nextt]=true;
            pre=nowt;
            for(int j=1;j<=k[nextt];j++)
            {
                now.push(nextt);
                nextg.push(graph[nextt][j]);
                //cout<<"now "<<nextt<<"nextg "<<graph[nextt][j]<<endl;
            }
        }
        
    }
    for(int i=1;i<=n;i++)
    {
        if(d[i]<0)
            d[i]=-1;
        cout<<i<<" "<<d[i]<<endl;
    }
   return 0;
}