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<iostream>
#include<algorithm>
#include<vector>
#include<cassert>
#include<cstdio>
#include<queue>

using namespace std;

int N, G[100][100], V[100], D[100];//G:２頂点,V:次数,D:距離

void bfs(int src){
    queue<int> Q;
    Q.push(src);
    fill(D, D + N, -1);
    D[src] = 0;
    while (! Q.empty()){
        int cur = Q.front();
        Q.pop();
        cerr << cur+1 << " " << D[cur] << endl;
        for (int k = 0; k < N; k++){
            if (G[cur][k] == 1 && D[k] < D[cur]){
                D[k] = D[cur]+1;
                Q.push(k);
            }
        }
    }
}

int main(){
	while (~scanf("%d", &N) && N){
		int id, c;
		for (int i = 0; i < N; i++){
			scanf("%d", &id); id--;//配列は0から始まるので、頂点番号を-1して考える。
			scanf("%d", V + id);
			for (int j = 0; j < V[id]; j++){
				scanf("%d", &c); c--;//配列は0から始まるので、頂点番号を-1して考える。
				G[id][c] = 1;
			}
		}//データの読み込み完了。
        bfs(0);
    }
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;


vector<int>v[105];
int t[105]={};
bool flag[105]={};
void BFS(int p)
{
	queue<int>Q;	
	Q.push(p);
	flag[p]=true;
	while(!Q.empty())
	{
		p=Q.front();
		Q.pop();
		for(int i=0;i<v[p].size();i++)
		{
			if(!flag[v[p][i]])
			{
				t[v[p][i]]=t[p]+1;
				Q.push(v[p][i]);
			}
			flag[v[p][i]]=true;
		}
	}
}
int main()
{	
	int n,a,b,k;
	cin>>n;
	for(int i=0;i<n;i++)
	{
		cin>>a>>k;
		for(int j=0;j<k;j++)
		{
			cin>>b;
			v[a].push_back(b);
		}
	}
	BFS(1);
	for(int i=1;i<=n;i++)
	{
		cout<<i<<" ";
		if(i!=1&&t[i]==0)cout<<-1<<endl;
		else cout<<t[i]<<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;
            //cout <<v<<" "<<d[v];
            d[v] = d[u] + 1;
            //cout <<"->"<< d[v] << endl;
            q.push(v);
        }
    }
    for(int i=0; i<n; i++){
        cout << i+1 << " " << ((d[i] == INFTY) ? (-1):d[i]) << endl;
    }
}

int main(){
    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 <bits/stdc++.h>
using namespace std;
#define _GLIBCXX_DEBUG

int main() {
  int n;
  cin >> n;
  vector<vector<int>> dst(n + 1);
  for (int i = 1; i <= n; i++) {
    int u, k;
    cin >> u >> k;
    for (int j = 0; j < k; j++) {
      int v;
      cin >> v;
      dst[i].push_back(v);
    }
  }
  queue<int> Q;
  vector<int> ans(n + 1, -1);
  ans[1] = 0;
  Q.push(1);
  while (Q.size()) {
    int p = Q.front();
    for (int d : dst[p]) {
      if (ans[d] == -1) {
        ans[d] = ans[p] + 1;
        Q.push(d);
      }
    }
    Q.pop();
  }
  for (int i = 1; i <= n; i++) {
    cout << i << ' ' << ans[i] << endl;
  }
}

C++: #include <algorithm>
#include <iostream>
#include <queue>
#include <vector>
using namespace std;
using Graph=vector<vector<int>>;
typedef long long ll;
int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};

int main(){
    int n;cin>>n;
    Graph G(n+2);
    for(int i=0;i<n;i++){
        int u,k;cin>>u>>k;
        for(int j=0;j<k;j++){
            int v;cin>>v;
            G[u].push_back(v);
        }
    }
    bool ans_check=false;
    vector<int> b(n+2,1000000);
    queue<int> q;
    b[1]=0;
    q.push(1);
    while(!q.empty()){
        int x=q.front();q.pop();
        for(int A=0;A<G[x].size();A++){
            int check_x=G[x][A];
            if(b[check_x]==1000000){
                q.push(check_x);
                b[check_x]=b[x]+1;
            }
        }
    }
    for(int i=1;i<n+1;i++){
        if(b[i]==1000000) b[i]=-1;
        cout<<i<<' '<<b[i]<<endl;
    }
}

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() {
  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;
    }
  }

  dfs(0);

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define REP(i,n) for(int i=0; i<(n); i++)
#define REP2(i,x,n) for(int i=x; i<(n); i++)
#define PRINT(x) cout<<(x)<<endl
#define INF 1000000000000 // 10^12
#define MOD 1000000007 // 10^9+7
#define PB push_back
#define MP make_pair

const int MAX_N = 100;

int n, u, k, v;

vector<int> G[MAX_N];
int d[MAX_N]; // distance from 0

int main() {
    // input
    cin >> n;
    REP(i, n) {
        cin >> u >> k;
        REP(j, k) {
            cin >> v;
            G[u-1].PB(v-1);
        }
    }

    // init d
    REP(i, n) d[i] = -1;

    // BFS
    queue<int> Q;
    Q.push(0);
    d[0] = 0;
    while (Q.size()) {
        int pos = Q.front(); Q.pop();
        REP(i, G[pos].size()) {
            int to = G[pos][i];
            if (d[to] != -1) continue;
            Q.push(to);
            d[to] = d[pos] + 1;
        }
    }

    // output
    REP(i, n) {
        int id = i + 1;
        printf("%d %d\n", id, d[i]);
    }

    return 0;
}