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();

		for (int k = 0; k < N; k++){

			if (G[cur][k] == 1 && D[k] == -1){

				D[k] = D[cur] + 1;

				Q.push(k);

			}

		}

	}

	for (int l = 0; l < N; l++){

		cerr << l + 1 << " " << D[l] << endl;

	}

}



int main(){

	scanf_s("%d", &N);

	int id, c;

	for (int i = 0; i < N; i++){

		scanf_s("%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_s("%d", V + id);

		for (int j = 0; j < V[id]; j++){

			scanf_s("%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>
#ifdef _DEBUG
#include "debug.hpp"
#else
#define debug(...)
#endif
#define REP(i, m, n) for(int (i) = (m); (i) < (n); ++i)
#define rep(i, n) REP(i, 0, n)
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
const int INF = 1e9 + 7;
const ll LINF = 1LL << 60;
template <class T, class U>
inline bool chmax(T &a, const U &b) {
  if(a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T, class U>
inline bool chmin(T &a, const U &b) {
  if(a > b) {
    a = b;
    return true;
  }
  return false;
}

int n;
vector<int> g[100];

int main() {
  cin.tie(0); ios::sync_with_stdio(false);
  cin >> n;
  rep(i,n) {
    int u, k;
    cin >> u >> k;
    --u;
    rep(j,k) {
      int v;
      cin >> v;
      --v;
      g[u].push_back(v);
    }
  }
  queue<int> q;
  q.push(0);
  vector<int> dst(n, -1);
  dst[0] = 0;
  while(!q.empty()) {
    int v = q.front();
    q.pop();
    for(int u : g[v]) {
      if(dst[u] != -1) continue;
      dst[u] = dst[v]+1;
      q.push(u);
    }
  }
  rep(i,n) cout << i+1 << " " << dst[i] << '\n';
  return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <map>
#include <set>
#include <vector>
#include <stack>
#include <queue>
#include <bitset>
#include <algorithm>
#include <numeric>
#include <functional>
using namespace std;

#define Rep(b, e, i) for(int i = b; i <= e; i++)
#define Repr(e, b, i) for(int i = e; i >= b; i--)
#define rep(n, i) Rep(0, n-1, i)
#define repr(n, i) Repr(n-1, 0, i)
#define all(v) (v).begin(), (v).end()
#define pb(v) push_back(v)
#define uniq(v) (v).erase(unique(all(v)),(v).end())
#define bitcnt(x) __builtin_popcount(x)
#define fst first
#define snd second
#define Pqaz(T) priority_queue<T,vector<T>,greater<T>>
#define Pqza(T) priority_queue<T>
#define ENJYU std::ios::sync_with_stdio(false);std::cin.tie(0);

typedef long long ll;
typedef pair<ll, ll> llP;
typedef pair<int, int> intP;

//vector の中身を出力
template <class T>ostream &operator<<(ostream &o,const vector<T>&v)
{o<<"{";for(int i=0;i<(int)v.size();i++)o<<(i>0?", ":"")<<v[i];o<<"}";return o;}

const int MAX = 128;

vector <int> adj[MAX];
int d[MAX];

void solve(void){
	ENJYU;
	int N;
	cin >> N;
	rep(N, i) {
		int u, k;
		cin >> u >> k;
		u--;
		rep(k, i) {
			int v;
			cin >> v;
			v--;
			adj[u].pb(v);
		}
	}
	memset(d, -1, sizeof(d));
	queue <int> q;
	q.push(0);
	d[0] = 0;
	while (!q.empty()) {
		int n = q.front();
		q.pop();
		for (int nv : adj[n]) {
			if (d[nv] > 0) continue;
			d[nv] = d[n] + 1;
			q.push(nv);
		}
	}

	rep(N, i) cout << i+1 << ' ' << d[i] << endl;

}

int main(void){
	solve();
	//cout << "yui(*-v・)yui" << endl;
	return 0;
}

C++: //Breadth First Search
#include <iostream>
#include <queue>

using namespace std;

static const int N = 100;

int n, M[N][N];
int d[N];
queue<int> Q;

void bfs() {
    int u;
    for(int i = 0; i < N; i++) d[i] = -1;
    Q.push(0);
    d[0] = 0;
    while(!Q.empty()) {
        u = Q.front();
        for(int i = 0; i < n; i++) {
            if(M[u][i] == 1 && d[i] == -1) {
                Q.push(i);
                d[i] = d[u] + 1;
            }
        }
        Q.pop();
    }
    for(int i = 0; i < n; i++) {
        cout << i + 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;
        for(int j = 0; j < k; j++) {
            cin >> v;
            M[u - 1][v - 1] = 1;
        }
    }

    bfs();
}

C++: #include<cstdio>
#include<iostream>
#include<string>
#include<queue>
using namespace std;

int n,m[101][101];
int d[101],t=0,vis[101];
queue<int> q;

void bfs(){
    q.push(1);
    d[1] = 1;
    int u,v;
    while( !q.empty() ){
        u = q.front();
        q.pop();
        for( v = 1; v <= n; v++ ){
            if( m[u][v]==0 || d[v]) continue;
            d[v] = d[u]+1;
            q.push(v);
        }
    }
    for( int i = 1; i <= n; i++ ){
        cout << i << " " << (d[i]-1) << endl;
    }
}

int main(){
    int i,j,k,u,v,du;
    scanf("%d",&n);
    k = n;
    while(k--){
        scanf("%d",&u);
        scanf("%d",&du);
        while(du--){
            scanf("%d",&v);
            m[u][v]  = 1;
        }
    }
    bfs();
}

C++: #include <cmath>
#include <queue>
#include <iostream>
using namespace std;

int G[110][110] = {0}; /*G????????????????????????????????????????????????, ??????1?????¨??????????????????*/

int n;
int D[110]; /*D???????????????????¨?????????°????????????????????????????????????*/
void bfs(int src){
  
  // cerr << "bfs root = " << src << endl;
  queue<int> Q;
  Q.push(src);
  D[src] = 0;
  while(! Q.empty()) {
    int cur = Q.front();
    Q.pop();
    // cerr << "visiting " << cur << ' ' << D[cur] << endl;
    for(int i=1; i<=n; i++){
      if(G[cur][i]==1 && D[i]==0){
	D[i] = D[cur]+1;
	Q.push(i);
      }
    }
  }

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

int main(){

  cin >> n;
  int u, k;
  int v[100000];
  for(int i=0; i<n; i++){
    cin >> u >> k;
    for(int j=0; j<k; j++){
      cin >> v[j];
      G[i+1][v[j]] = 1;
    }
  }

  bfs(1);
}