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 <stdio.h>
#include <stdint.h>
#include <iostream>
#include <fstream>
#include <cassert>
#include <climits>

#include <memory>
#include <vector>
#include <queue>
using namespace std;

#define DEBUG (1)

#if DEBUG
#define DPRINTF(...) do { \
    printf("D(L%d) %s: ", __LINE__, __func__); \
    printf(__VA_ARGS__); \
  } while (false)
#else
#define DPRINTF(...)
#endif // DEBUG


struct Vertex {
  Vertex() :
    id_(-1),
    visited_(0),
    distance_(-1),
    adjNum_(-1) { }

  int id_;
  bool visited_;
  int distance_;
  int adjNum_;
  unique_ptr<int[]> adjIds_;

  void set(int id, vector<int> ids);
  void printInfo();
  void printDistance();
};


void Vertex::set(int id, vector<int> ids)
{
  id_ = id;
  adjNum_ = ids.size();

  if (adjNum_ == 0)
    return;

  adjIds_ = unique_ptr<int[]>(new int[adjNum_]);

  for (int i = 0; i < adjNum_; i++)
    adjIds_[i] = ids[i];
}


void Vertex::printInfo()
{
  DPRINTF("%d %d", id_, adjNum_);
  for (int i = 0; i < adjNum_; i++)
    printf(" %d", adjIds_[i]);
  cout << endl;
}


void Vertex::printDistance()
{
  printf("%d %d\n", id_, distance_);
}


void bfs(Vertex vertices[])
{
  const int startId = 1;
  queue<int> idQueue;

  idQueue.push(startId);

  int distance = 0;

  while (!idQueue.empty()) {

    DPRINTF("queue size %lu\n", idQueue.size());

    const size_t numOfThisDist = idQueue.size();

    for (size_t i = 0; i < numOfThisDist; i++)
    {
      int id = idQueue.front();
      idQueue.pop();

      DPRINTF("%zu  id %d\n", i, id);

      Vertex &vtx = vertices[id];

      if (vtx.visited_)
        continue;

      vtx.visited_ = true;
      vtx.distance_ = distance;

      for (int j = 0; j < vtx.adjNum_; j++)
        idQueue.push(vtx.adjIds_[j]);

    }

    distance++;
  }
}


int main() {
  int n;
  cin >> n; cin.ignore();

  DPRINTF("%d\n", n);

  // do not use [0], it's empty
  Vertex vertices[n+1];

  for (int i = 1; i <= n; i++)
  {
    int node, adjNum;

    cin >> node >> adjNum;

    vector<int> adjs;

    for (int j = 0; j < adjNum; j++)
    {
      int v;
      cin >> v;
      adjs.push_back(v);
    }

    vertices[i].set(node, adjs);

    cin.ignore();

  }

#ifdef DEBUG
  for (int i = 1; i <= n; i++)
    vertices[i].printInfo();
#endif // DEBUG

  bfs(vertices);

  for (int i = 1; i <= n; i++)
    vertices[i].printDistance();

  return 0;

}

C++: // C++ 14
#include <iostream>
#include <vector>
#include <array>
#include <list>
#include <algorithm>
#include <queue>
#include <stack>
#include <math.h>

#define ll long long
#define Int int
#define INTMAX (1 << 21)
#define loop(x, start, end) for(Int x = start; x < end; x++)
#define loopdown(x, start, end) for(Int x = start; x > end; x--)

using namespace std;


// 1 (0)
// 1 2 (1)
// 1 2 4 (1)
// 2 4 
// 2 4
// 4
// 4 3
// 3
// 
void bfs(vector<Int> vs[], Int n) {
    Int t = 0;
    bool visited[n];
    Int ds[n];
    
    loop(i,0,n) {
        visited[i] = false;
        ds[i] = -1;
    }
    
    queue<Int> Q;
    Int depth = 0;
    
    Q.push(0);
    visited[0] = true;
    ds[0] = 0;
    
    while (!Q.empty()) {
        Int parent = Q.front(); Q.pop();
        for (auto child: vs[parent]) {
            if (visited[child]) continue;
            Q.push(child);
            visited[child] = true;
            ds[child] = ds[parent] + 1;
        }
    }
    
    loop(i,0,n) cout << i+1 << " " << ds[i] << endl;
}


int main(void){
    Int n, x, cc, c;
    cin >> n;
    vector<Int> vs[n];
    loop(i,0,n) {
        cin >> x >> cc;
        loop(j,0,cc) {
            cin >> c;
            vs[x-1].push_back(c-1);
        }
        
    }
    bfs(vs, n);
}

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];   // 距離で訪問状態 (color) を管理する

void bfs(int s) {
    queue<int> q;
    int i;
    int u, v;

    q.push(s);
    for (i = 0; i < n; i++) d[i] = INFTY;
    d[s] = 0;

    while (!q.empty()) {
        u = q.front(); q.pop();
        for (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 (i = 0; i < n; i++) {
        cout << i + 1 << " " << ((d[i] == INFTY) ? (-1) : d[i]) << endl;
    }
}

int main()
{
    int u, k, v;
    int i, j;

    cin >> n;
    for (i = 0; i < n; i++) {
        for (j = 0; j < n; j++) M[i][j] = 0;
    }

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

    bfs(0);

    return 0;
}

C++: #include <stdio.h>
#include <vector>
#include <queue>
using namespace std;

vector<int> G[101];
bool visit[101];
int n, u, k, m;
int dist[101];

void bfs()
{
	int root = 1;
	queue<int> que;
	que.push(root);
	dist[1] = 0;
	while (!que.empty())
	{
		int node = que.front();
		que.pop();
		for (int i = 0; i < G[node].size(); i++)
		{
			int next = G[node][i];
			if (!visit[next])
			{
				visit[next] = true;
				que.push(next);
				dist[next] = dist[node] + 1;
			}
		}
	}
}

int main()
{
	for (int i = 0; i < sizeof(dist) / sizeof(dist[0]); i++)
		dist[i] = -1;
	scanf("%d", &n);
	for (int i = 0; i < n; i++)
	{
		scanf("%d%d", &u, &k);
		for (int j = 0; j < k; j++)
		{
			scanf("%d", &m);
			G[u].push_back(m);
		}
	}
	bfs();
	for (int i = 1; i <= n; i++)
		printf("%d %d\n", i, dist[i]);

	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
template <class T>
bool chmax(T& a, const T& b)
{
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T>
bool chmin(T& a, const T& b)
{
    if (b < a) {
        a = b;
        return 1;
    }
    return 0;
}

#define rep(i, n) for (int i = 0; i < (int)n; i++)
#define all(x) (x).begin(), (x).end() //sortなどの引数を省略したい
#define F first
#define S second

typedef long long ll;
const ll MOD = 1e9 + 7;
const int inf = 1000000;
const int minf = -1000000;
const ll lnf = 1e12;
const ll mlnf = -1e12;

// Graph problem
using Graph = vector<vector<int>>;
int dx[4] = { 1, 0, -1, 0 };
int dy[4] = { 0, 1, 0, -1 };

// coding start

int main()
{
    int N;
    cin >> N;
    Graph G(N);
    rep(i, N)
    {
        int hoge, k;
        cin >> hoge >> k;
        rep(j, k)
        {
            int tmp;
            cin >> tmp;
            tmp--;
            G[i].push_back(tmp);
        }
    }
    vector<int> dist(N, -1);
    dist[0] = 0;
    queue<int> que;
    que.push(0);
    while (!que.empty()) {
        int v = que.front();
        que.pop();
        for (auto nv : G[v]) {
            if (dist[nv] != -1)
                continue;
            dist[nv] = dist[v] + 1;
            que.push(nv);
        }
    }
    rep(i, N) printf("%d %d\n", i + 1, dist[i]);
}