Go: package main

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

type vertexId int

type vertex struct {
	id vertexId
	visitedAt int
	adjs []vertexId
}

func createVertex(id int, adjsInt []int) vertex {
	adjs := make([]vertexId, len(adjsInt))
	for i := 0; i < len(adjs); i++ {
		adjs[i] = vertexId(adjsInt[i])
	}
	return vertex{
		id: vertexId(id),
		visitedAt: -1,
		adjs: adjs,
	}
}

func (v *vertex) isVisited() bool {
	return v.visitedAt >= 0
}

func bfs(id vertexId, vqueue []vertexId, vertices []vertex) {
	vertex := &vertices[id-1]
	for _, vid := range vertex.adjs {
		if !vertices[vid-1].isVisited() {
			(&vertices[vid-1]).visitedAt = vertex.visitedAt+1
			vqueue = append(vqueue, vid)
		}
	}
	if len(vqueue) > 0 {
		nextId := vqueue[0]
		nextVqueue := vqueue[1:]
		bfs(nextId, nextVqueue, vertices)
	}
}

func solveBfs(vertices []vertex) {
	vertex := &vertices[0]
	vertex.visitedAt = 0
	vqueue := make([]vertexId, 0)
	bfs(vertex.id, vqueue, vertices)
}

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

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

	vertices := make([]vertex, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjN, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjs := make([]int, adjN)
		for j := 0; j < adjN; j++ {
			adjId, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjs[j] = adjId
		}
		vertices[i] = createVertex(id, adjs)
	}

	solveBfs(vertices)

	for i := 0; i < n; i++ {
		fmt.Printf("%d %d\n", vertices[i].id, vertices[i].visitedAt)
	}
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

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

C++: #include <bits/stdc++.h>
typedef long long ll;
using namespace std;
ll MOD = 1000000007;

#define vec                vector<int>
#define vecll              vector<ll>
#define vecd               vector<double>
#define vecst              vector<string>
#define vecb               vector<bool>
#define vec2(var, n, m)    vector<vector<int>> var(n, vector<int>(m, 0))
#define vecll2(var, n, m)  vector<vector<ll>> var(n, vector<ll>(m, 0))

#define rep(i,n)         for(ll i=(ll)0; i<(ll)n; i++)
#define REP(i,m,n)       for(ll i=(ll)m; i<(ll)n; i++)
#define arr(var, n)      vec var(n); rep(i,n){cin >> var[i];}
#define arrll(var, n)    vecll var(n); rep(i,n){cin >> var[i];}
#define arrst(var, n)    vecst var(n); rep(i,n){cin >> var[i];}
#define all(var)         (var).begin(), (var).end()
#define sortall(var)     sort(all(var))
#define uniqueall(v)     v.erase(unique(v.begin(), v.end()), v.end());
#define f_sum(var)       accumulate(all(var), 0)
#define f_sumll(var)     accumulate(all(var), 0LL)
#define chmin(v1, v2)    v1 = min(v1, v2)
#define chmax(v1, v2)    v1 = max(v1, v2)
#define pb(var)          push_back(var)
#define prt(var)         cout << (var) << "\n"
#define prtd(n, var)     cout << fixed << setprecision(n) << (var) << "\n"
#define prtfill(n, var)  cout << setw(n) << setfill('0') << (var);
#define prt2(v1, v2)     cout << (v1) << " " << (v2) << "\n"
#define prt3(v1, v2, v3) cout << (v1) << " " << (v2) << " " << (v3) << "\n"
#define prtall(v)        rep(i,v.size()){cout<<v[i]<<(i!=v.size()-1?" ":"\n");}
void prtok(bool ok){prt(ok ? "yes" : "no");}
//----------------------------------------------------------------
class Graph{

public:
  vector<vector<int>> graphs;
  vector<bool> check; // For DFS
  vector<ll> dist;   // For BFS
  queue<int> q; // For BFS

  Graph(int n){
    graphs.resize(n);
    init(n);
  }
  ~Graph(){}

  void addedge(int u, int v){
    u--; v--;
    graphs[u].push_back(v);
    //graphs[v].push_back(u);
  }

  void addedge_cin(int m){
    rep(i,m){
      int a, b;
      cin >> a >> b;
      addedge(a, b);
    }
  }

  void init(int n){
    check.resize(n, false);
    dist.resize(n, -1);
  }

  void reset(){
    rep(i,check.size()){
      check[i]=false;
      dist[i]=-1;
    }
  }

  void dfs(int v)
  {
    check[v] = true;

    for(auto next_v : graphs[v]){
      if(check[next_v]) continue;
      dfs(next_v);
    }
  }

  void bfs(int v)//----------------------
  {
    dist[v] = 0;
    q.push(v);

    while(!q.empty()){
      int cur_v = q.front();
      q.pop();

      for(int next_v : graphs[cur_v]){
        if(dist[next_v] != -1){
          continue;
        }

        dist[next_v] = dist[cur_v] + 1;
        q.push(next_v);
      }
    }
  }//-----------------------

};

int main(void) {
  int n;
  cin >> n;
  Graph g(n);

  rep(i,n){
    int ver, num;
    cin >> ver >> num;
    rep(j,num){
      int tmp;
      cin >> tmp;
      g.addedge(ver, tmp);
    }
  }

  g.bfs(0);

  rep(i,n){
    prt2(i+1, g.dist[i]);
  }

}

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++){
     if(d[i]==INF) d[i]=-1;
     cout<<i<<" "<<d[i]<<endl;
   }
    return 0;
}

C++: #include <iostream>
#include <queue>
 
using namespace std;
 
int D[110]={0};
void bfs(int src,int n,int g[110][110]){
 
queue<int> Q;
Q.push(src);
D[src]=0;
while (! Q.empty()){
    int cur =Q.front();
    Q.pop();
    for(int r=0;r<n;r++){
        if (g[cur][r]==1&&D[r]==0){
            D[r]=D[cur]+1;
            Q.push(r);
        }
    }
}
}
int main() {
int n,g[110][110]={0};
cin>>n;
int j,num,t;
for(int k=0;k<n;k++){
cin>>j>>num;
for(int kk=0;kk<num;kk++){
    cin>>t;
    g[k][t-1]=1;
}
}
bfs(0,n,g);

for(int a=0;a<n;a++){
    if(D[a]!=0){
    cout<<a+1<<" "<<D[a]<<endl;
}
else{
	if (a!=0){
    cout<<a+1<<" -1"<<endl;
}
	else{
		cout<<a+1<<" 0"<<endl;
	}
}
}
    return 0;
}

C++: #include<iostream>
#include<queue>
using namespace std;
static const int N = 100;
static const int INFTY = (1<<21);

int n,M[N][N];
int d[N];

void bfs( int s ){
  queue<int> q;
  q.push(s);
  for( int i = 0 ; i < n ; i++ ){
    d[i] = INFTY;
  }
  d[s] = 0;int u;
  while( !q.empty() ){
    u = q.front();
    q.pop();
    for( int v = 0 ; v < n ; v++ ){
      if( M[u][v] == 0 )continue;
      if( d[v] != INFTY )continue;
      d[v] = d[u] + 1;
      q.push(v);
    }
  }
  for( int i = 0 ; i < n ; i++ ){
    cout << i + 1 << " " <<((d[i] == INFTY) ? ( -1 ) : d[i]) << endl;
  }
}

int main( void ){
  int u,k,v;
  cin >> n;
  for( int i = 0 ; i < n ; i++ ){
    for( int j = 0 ; j < n ; j++ ){
      M[i][j] = 0;
    }
  }

  for( int i = 0 ; i < n ; i++ ){
    cin >> u >> k;
    u--;
    for( int j = 0 ; j < k ; j++ ){
      cin >>v;
      v--;
      M[u][v] = 1;
    }
  }
  bfs(0);

  return 0;
}

C++: #include<iostream>
#include<queue>
using namespace std;
static const int INF=(1<<21);
int n,M[101][101];
int d[101];
void bfs(int s){
  queue<int>q;
  q.push(s);
  for(int i=0;i<n;++i) d[i]=INF;
  d[s]=0;
  while(!q.empty()){
    int u=q.front();
    q.pop();
    for(int v=0;v<n;++v){
      if(M[u][v]==0) continue;
      if(d[v]!=INF) continue;
      d[v]=d[u]+1;
      q.push(v);
    }
  }
  for(int i=0;i<n;++i){
    cout<<i+1<<" "<<( (d[i]==INF)?(-1):d[i] )<<endl;
  }
}
int main(){
  int u,v,k;
  cin>>n;
   for(int i=0;i<n;++i){
    cin>>u>>k;
    u--; //頂点番号をあわせてる
    for(int j=0;j<k;++j){
      cin>>v;
      v--;
      M[u][v]=1;
    }
   }
   bfs(0);
   return 0;
}