Go: package main

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

func main() {
	scn := bufio.NewScanner(os.Stdin)
	scn.Split(bufio.ScanWords)
	nextInt := func() int { scn.Scan(); r, _ := strconv.Atoi(scn.Text()); return r }
	w := bufio.NewWriter(os.Stdout)

	n := nextInt()
	vecs := make([][]int, n)
	for i := 0; i < n; i++ {
		u := nextInt()
		k := nextInt()
		for j := 0; j < k; j++ {
			vecs[u-1] = append(vecs[u-1], nextInt()-1)
		}
	}

	ds := make([]int, 0, n)
	for i := 0; i < n; i++ {
		ds = append(ds, -1)
	}

	q := make([]int, 0, n)
	q = append(q, 0)
	ds[0] = 0

	for len(q) > 0 {
		i := pop(&q)
		for _, v := range vecs[i] {
			if ds[v] == -1 {
				ds[v] = ds[i]+1
				q = append(q, v)
			}
		}
	}

	for i, d := range ds {
		fmt.Fprintln(w, i+1, d)
	}

	w.Flush()
}

func pop(q *[]int) int {
	v := (*q)[0]
	*q = (*q)[1:]
	return v
}

C++: #include <iostream>
#include <iomanip>
#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <bitset>
#include <climits>
#define REP(i,n) for (int i=0;i<(n);i++)
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define RFOR(i,a,b) for (int i=(a)-1;i>=(b);i--)
#define ll long long
#define ull unsigned long long
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
const int INF = 1e9;
const int MOD = 1e9 + 7;

using namespace std;



int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
	int n;
	cin>>n;
	vector<vector<int> > edge(n,vector<int>());
	REP(i,n){
		int v;cin>>v;v--;int t;cin>>t;
		while(t--){
			int u;cin>>u;u--;
			edge[v].push_back(u);
		}
	}
	queue<pair<int,int> > que;
	int mindist[103];
	fill_n(mindist,n,INF);
	mindist[0] = 0;
	que.push(make_pair(0,0));
	while(!que.empty()){
		pair<int,int> v = que.front();
		que.pop();
		v.second++;
		REP(i,edge[v.first].size()){
			if(v.second < mindist[edge[v.first][i]]){
				mindist[edge[v.first][i]] = v.second;
				que.push(make_pair(edge[v.first][i],v.second));
			}
		}
	}
	REP(i,n){
		cout << i+1 << ' ' << mindist[i] << endl;
	}
  return 0;
}

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

int main() {
   int n;
   cin >> n;
   vector<vector<int>> G(n+1);
   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);
       }
   }
   vector<int> c(n+1,-1);
   queue<int> q;
   q.push(1);
   c[1]=0;
   while(!q.empty()) {
       int a=q.front();
       q.pop();
       for (auto b:G[a]){
           if (c[b]==-1) {
           q.push(b);c[b]=true;c[b]=c[a]+1;
           }
       }
   }
   for (int i=0; i<n; i++) {
       cout << i+1 << " " << c[i+1] << endl;
   }
}

C++: //16D8103013E Sen Shunkou
#include<iostream>
#include<queue>
int n;
int cnt=0;

int main(){
    //input
    int n;
    std::cin>>n;

    int cnt=0;
    int A[100][100];
    int dis_min[n];
    bool visited[n];

    for(int i=0;i<n;i++){
        for(int j=0;j<n;j++){
            A[i][j]=0;
        }
    }

    for(int i=0;i<n;i++){
        std::cin>>A[i][0];
        std::cin>>A[i][1];
        for(int j=0;j<A[i][1];j++){
            std::cin>>A[i][j+2];
        }
    }

    for(int i=0;i<n;i++){
        dis_min[i]=0;
    }

    //initialization
    std::queue<int> que;
    que.push(0);
    //std::cout<<"\n"<<que.front()<<"\n";
    //std::cout<<que.size()<<"\n\n";

    while(!que.empty()){
        int q=que.size();
        for(int k=0;k<q;k++){
            //std::cout<<"quesize"<<que.size()<<"\n";
            int i=que.front();
            que.pop();
            visited[i]=true;
            dis_min[i]=cnt;
            //std::cout<<i<<"cnt"<<cnt<<"\n";
            if(A[i][1]!=0){
                for(int j=0;j<A[i][1];j++){
                    if(visited[A[i][j+2]-1]!=true){
                        visited[A[i][j+2]-1]=true;
                        que.push(A[i][j+2]-1);
                        //std::cout<<A[i][j+2]-1<<"\n";
                    }
                }
            }
        }
        cnt++;
        //std::cout<<"cnt="<<cnt<<"\n";
    }

    //std::cout<<"===========\n";
    for(int i=0;i<n;i++){
        std::cout<<i+1<<" "<<dis_min[i]<<"\n";
    }
    return 0;
}

C++: #include<bits/stdc++.h>
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;
  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]!=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,k,v;

  cin>>n;

  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<algorithm>
#include<cstdio>
#define INF 1<<30
#define MAX 100000
using namespace std;

class Queue{
private:
  int inf[MAX];
  int head,tail;
 
public:
 
  Queue(){
    syokika();
  }
 
  void syokika(){
    head = 0;
    tail = 0;
  }
 
  void push(int x){
    inf[tail]=x;
    if(MAX == tail+1)tail = 0;
    else tail++;
  }
 
  void pop(){
    if(MAX == head+1)head=0;
    else head++;
  }
 
  int front(){
    return inf[head];
  }
 
  bool empty(){
    if(tail - head == 0)return true;
    else return false;
  }
 
  int size(){
    return tail - head;
  }
 
};

int imap[200][200];
int k[200] = {0}; 
int ans[200] = {0};
bool used[200];

int main(){
  int n,u[1000];
  cin >> n;
  for(int i=0;i<200;i++)for(int j=0;j<200;j++)imap[j][i] = INF;  
  for(int i=0;i<n;i++){
    cin >> u[i];
    cin >> k[u[i]];
    for(int j=0;j<k[u[i]];j++){
      cin >> imap[u[i]][j];
    }
  }

  sort(u,u+n);

  /*
  for(int i=0;i<n;i++){
    for(int j=0;j<k[u[i]];j++){
      cout << imap[u[i]][j] << " ";
    }
    cout << endl;
  }
  */

  Queue que = Queue();

  que.push(u[0]);

  while(!que.empty()){
    int p = que.front(); que.pop();
    for(int i=0;i<k[p];i++){
      if(!used[imap[p][i]]){
	que.push(imap[p][i]);//cout << "push!= " << imap[p][i] << endl;
	used[imap[p][i]] = true;
	ans[imap[p][i]] = ans[p] + 1;
      }
    }
  }


 
  for(int i=0;i<n;i++){
    cout << u[i] << " " << ans[u[i]] << endl;
  }

  return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
using Graph =vector<vector<int>>;
vector<bool> visit(100,false);
#define mp make_pair
vector<int> dis(100,-1);

void bfs(int s,Graph graph)
{
    int n=graph.size();
    queue<int> que;
    dis[s]=0;
    visit[0]=true;
    que.push(s);
    int v,u;
    while (!que.empty())
    {
        v=que.front();
        que.pop();
        for (int i=0;i<n;i++)
        {
            if (!visit[i] && graph[v][i])
            {
                visit[i]=true;
                dis[i]=dis[v]+1;
                que.push(i);
            }
        }
    }
}

int main()
{
    int n;cin >> n;
    Graph graph(n,vector<int> (n,0));
    int v,k,u;
    for (int i=0;i<n;i++)
    {
        cin >> v;
        cin >> k;
        for (int j=0;j<k;j++)
        {
            cin >>u;
            graph[v-1][u-1]=1;
        }
    }
    bfs(0,graph);
    for (int i=0;i<n;i++)
    {
        cout << i+1<<" "<<dis[i] << endl;
    }
    return 0;
}