Go: package main

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

var distance []int

type queue struct {
	q    []int
	head int
	tail int
}

func (q *queue) push(n int) {
	q.q[q.tail] = n
	q.tail++
}

func (q *queue) pop() int {
	q.head++
	return q.q[q.head-1]
}

func (q *queue) isEmpty() bool {
	return q.head == q.tail
}

func makeAdjList() [][]int {
	var n int
	fmt.Scanf("%d", &n)

	adj := make([][]int, n)
	for i := 0; i < n; i++ {
		adj[i] = make([]int, n)
	}

	sc := bufio.NewScanner(os.Stdin)
	for i := 0; i < n; i++ {
		sc.Scan()
		nodeInfo := strings.Split(sc.Text(), " ")
		outDegree, _ := strconv.Atoi(nodeInfo[1])

		if outDegree > 0 {
			for k := 0; k < outDegree; k++ {
				j, _ := strconv.Atoi(nodeInfo[k+2])
				j-- // convert 1 based to 0 based
				adj[i][j] = 1
			}
		}
	}

	return adj
}

func bfs(graph [][]int, s int) {
	distance = make([]int, len(graph))

	infty := -1
	for i := 0; i < len(distance); i++ {
		distance[i] = infty
	}
	distance[s] = 0

	q := &queue{make([]int, 1000), 0, 0}
	q.push(s)

	for !q.isEmpty() {
		u := q.pop()
		for i := 0; i < len(graph); i++ {
			if graph[u][i] == 0 {
				continue // u, i間に辺がない場合
			}
			if distance[i] != infty {
				continue // 訪問済みの場合
			}
			// 訪問するnodeの始点からの距離を設定し、訪問キューに入れる
			distance[i] = distance[u] + 1
			q.push(i)
		}
	}

	// print distance
	for i, d := range distance {
		fmt.Printf("%d %d\n", i+1, d)
	}
}

func main() {
	adj := makeAdjList()
	bfs(adj, 0)
}

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

typedef long long ll;
typedef pair<ll, ll> P;

#define pb push_back
#define rep(i, n) for(int i = 0; i < (n); i++)
#define FOR(i, a, n) for(int i = a; i < (n); i++)
#define mod (ll)(1e9+7)
#define int ll

#define N 100
#define no -1

__attribute__((constructor))
void initial() {
  cin.tie(0);
  ios::sync_with_stdio(false);
}

ll graph[N][N] = {{}}, d[N] = {}, n;

void bfs(int v) {
  queue<int> q;
  q.push(v);
  ll u;
  for(int i = 1; i <= n; i++) d[i] = no;
  d[v] = 0;
  while(!q.empty()) {
    u = q.front(); q.pop();
    for(int i = 1; i <= n; i++) {
      if(graph[u][i] == 0) continue;
      if(d[i] != no) continue;
      d[i] = d[u] + 1;
      q.push(i);
    }
  }
}

signed main() {
	ll u, v, k;
  cin >> n;
  rep(i, n) {
    cin >> u >> k;
    rep(j, k) {
      cin >> v;
      graph[u][v] = 1;
    }
  }

  bfs(1);

  for(int i = 1; i <= n; i++) {
    cout << i << " " << d[i] << endl;
  }

	return 0;
}

C++: #include<cstdio>
#include<queue>
using namespace std;
static const int INF=(1<<21);
static const int MAXN=101;
int main()
{
	int n,m[MAXN][MAXN],i,j,u,k,v,l,o,c=1,t[MAXN];
	queue<int> 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;
		}
	}
	q.push(1);
	used[1]=true;
	t[1]=0;
	while(!q.empty()){
		l=q.front();
		q.pop();
		o=0;
		for(i=1;i<n+1;i++){
			if(m[l][i]==1&&used[i]==false){
				q.push(i);
				used[i]=true;
				t[i]=c;
				o=1;
			}
		}
		if(o==1){
			c++;
		}
	}
	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"

using namespace std;

using ll = long long;

template<typename T> using V = std::vector<T>;
using Vi = V<int>;
using VVi = V<V<int>>;
using Vl = V<ll>;
using VVl = V<V<ll>>;
using Vs = V<string>;

template<typename T1, typename T2> using P = std::pair<T1, T2>;
using Pii = P<int, int>;
using Pll = P<ll, ll>;
using Pdd = P<double, double>;

template<typename T1, typename T2> using M = std::map<T1, T2>;
using Mii = M<int, int>;
using Msi = M<string, int>;

#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define REP2(i,s,e) for(int i=(int)(s);i<(int)(e);++i)
#define RREP(i,s,e) for(int i=(int)(s);i>=(int)(e);--i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin(),ie=(c).end();i!=ie;++i)
#define ALL(c) (c).begin(), (c).end()

const double PI = acos(-1);
const ll MOD = 1e9+7;

int n;
string s;

int main() {
    cin >> n;
    VVi edges(n);
    REP(i, n) {
        int u, k;
        cin >> u >> k;
        edges[i] = Vi(k);
        REP(j, k) {
            int v;
            cin >> v;
            v--;
            edges[i][j] = v;
        }
    }

    Vi dis(n, -1);
    queue<int> q;
    q.push(0);
    dis[0] = 0;
    while (!q.empty()) {
        int node = q.front();
        q.pop();
        FOR(i, edges[node]) {
            if (dis[*i] == -1) {
                dis[*i] = dis[node] + 1;
                q.push(*i);
            }
        }
    }
    REP(i, n) {
        printf("%d %d\n", i+1, dis[i]);
    }

    return 0;
}

C++: //
//  main.cpp
//  BFS
//  Copyright ?????? 2017 1. All rights reserved.
//

#include <iostream>
#include <vector>
#include <queue>
#include <cmath>
using namespace std;


int main() {
    int n,u,k,d;
    vector<vector<int>>A(100,vector<int>(100));
    for(int i=0;i<100;i++)
        for(int j=0;j<100;j++)
            A[i][j]=0;
    
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>u>>k;
        for(int j=0;j<k;j++){
            cin>>d;
            A[u-1][d-1]=1;
        }
    }//input
    
    int D[100];
    for(int i=0;i<100;i++) D[i]=100000000;
    int src=0;
    queue<int>Q;
    Q.push(src);
    D[src]=0;
        while(!Q.empty()){
            int cur=Q.front();
            Q.pop();
            for(int dst=0;dst<n;dst++)
            {
                if(A[cur][dst]==1&&D[dst]==100000000){
                    
                    D[dst]=min(D[cur]+1,D[dst]);
                    Q.push(dst);
                }
        }
    }
    
    for(int i=0;i<n;i++){
        
        cout<<i+1<<" "<<D[i]<<endl;
    }
    
    

    
    
    }

C++: #include<iostream>
#include<queue>
using namespace std;
void debug1();
int n, gragh[110][110] = {}, d[110] = {};
queue<int> q;

int main() {
	cin >> n;
	//input
	for (int i = 0; i < n; i++) {
		int u,k;
		cin >> u >> k;
		for (int j = 0; j < k; j++) {
			int t;
			cin >> t;
			gragh[u][t] = 1;
		}
	}
	//debug1();
	//search
	d[1] = 0;
	q.push(1);
	while (!q.empty()) {
		int cur = q.front();
		q.pop();
		//cerr << "visiting " << cur << " Distance: " << d[cur] << endl;
		for (int i = 1; i <= n; i++) {
			if (d[i] == 0 && gragh[cur][i] == 1) {
				d[i] = d[cur] + 1;
				q.push(i);
			}
		}
	}

	//from 0 to 1
	for (int i = 2; i <= n; i++) {
		if (d[i] == 0) d[i] = -1;
	}

	//output
	for (int i = 1; i <= n; i++) {
		cout << i << " " << d[i] << endl;
	}
	return 0;
}

void debug1() {
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= n; j++) {
			cerr << gragh[i][j] << " " ;
		}
		cerr << endl;
	}
}

C++: #include <iostream>
#include <algorithm>
#include <string>
#include <stack>
#include <cstdlib>
#include <queue>
#include <vector>
#include <set>

using namespace std;
int n,m,l,p;
bool a[100][100];
int D[100];
void  bfs ( int src) {
	queue<int> Q;
	Q.push(src);
	D[src]=0;
	while( ! Q.empty() ) {
		int cur = Q.front();
		Q.pop();
		for(int dst = 0; dst < n; dst++ ) {
			if( D[dst] == 0 && a[cur][dst] == 1 ) {
				D[dst] = D[cur] + 1;
				Q.push(dst);
			}
		}
	}
	for (int i = 0; i < n;i++) {
	cerr << i+1 <<  " " << D[i] << endl;
	}
}
int main() {
	cin >> n;
	for (int i = 0;i < n; i++){
		cin >> m;
		cin >> l;
		for(int j = 0; j < l;j++) {
			a[i][j] = 0;
			cin >> p;
			a[m-1][p-1] = 1;
		}
	}
		bfs(0);
	
}