Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
type Queue struct {
	arr []int
}

func (q *Queue) push(v int) {
	q.arr = append(q.arr, v)
}

func (q *Queue) pop() int {
	res := q.arr[0]
	q.arr = q.arr[1:]
	return res
}

func (q *Queue) isEmpty() bool {
	return len(q.arr) == 0
}

func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	G := make([][]int, N)
	for i := 0; i < N; i++ {
		u, k := sc.nextInt()-1, sc.nextInt()
		for j := 0; j < k; j++ {
			G[u] = append(G[u], sc.nextInt()-1)
		}
	}
	var q Queue
	seen := make([]int, N)
	for i := 0; i < N; i++ {
		seen[i] = -1
	}
	var search func(cur int)
	search = func(cur int) {
		for i := 0; i < len(G[cur]); i++ {
			next := G[cur][i]
			if seen[next] == -1 {
				q.push(next)
				seen[next] = seen[cur] + 1
			}
		}
	}
	q.push(0)
	seen[0] = 0
	for !q.isEmpty() {
		search(q.pop())
	}

	for i := 0; i < N; i++ {
		fmt.Fprintln(wtr, i+1, seen[i])
	}
	wtr.Flush()
}

C++: #include <iostream>
#include <algorithm>
#include <queue>
#define MAX_V 101
#define INF 10000000
using namespace std;

bool edge[MAX_V][MAX_V];
int dist[MAX_V];

void bfs(int start, int n) {
  queue<int> que;
  que.push(start);
  dist[start] = 0;
  int current;
  while (!que.empty()) {
    current = que.front();
    que.pop();
    for (int i = 1; i <= n; i++) {
      if (edge[current][i] && dist[i] == INF) {
	dist[i] = dist[current] + 1;
	que.push(i);
      }
    }
  }
}

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

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

  for (int i = 1; i <= n; i++) {
    dist[i] = INF;
  }

  bfs(1, n);

  for (int i = 1; i <= n; i++) {
    cout << i << ' ';
    if (dist[i] == INF) cout << -1 << endl;
    else cout << dist[i] << endl;
  }
}

C++: #include <iostream>
#include <vector>
#include <queue>
using namespace std;
int main()
{
    int n; cin >> n;
    vector< vector<int> > g(n, vector<int>());
    for (int i = 0; i < n; i++)
    {
        int u, k; cin >> u >> k; u--;
        for (int j = 0; j < k; j++)
        {
            int v; cin >> v; v--;
            g[i].push_back(v);
        } 
    }
    vector<bool> seen(n, false);
    vector<int> d(n, -1); d[0] = 0;
    queue<int> q;
    q.push(0);
    int depth = 0;
    while (!q.empty())
    {
        depth++;
        queue<int> qt;
        while (!q.empty())
        {
            qt.push(q.front()); 
            q.pop();
        }
        while (!qt.empty())
        {
            int x = qt.front(); qt.pop();
            seen[x] = true;
            for (int i = 0; i < g[x].size(); i++)
            {
                if(d[g[x][i]] == -1) d[g[x][i]] = depth;
                if (seen[g[x][i]] == false) q.push(g[x][i]);
            }
        }
    }
    for (int i = 0; i < n; i++)
        cout << i + 1 << " " << d[i] << endl;
}

C++: // -*- mode:c++; coding:utf-8; c-basic-offset:2; -*-
// ALDS1_11_C: Breadth First Search

#include <algorithm>
#include <cstdio>
#include <queue>

using uint = unsigned int;

class Graph {
  const uint n_;
  uint* const g_;
  int* const depth_;
  
public:
  Graph(uint n) : n_(n),
                  g_(new uint[(n_*n_)]),
                  depth_(new int[n])
  {
    std::fill(g_, g_+(n_*n_), 0u);
  }

  ~Graph()
  {
    delete[] g_;
    delete[] depth_;
  }
  
  uint* operator [](uint i) const { return g_+(n_*i); }

  int* depth() const { return depth_; }

  void bfs()
  {
    init_depth();
    std::queue<uint> q;
    auto i = 0u;
    q.push(i);
    depth_[i] = 0;
    auto last_visit = i;
    while (!q.empty()) {
      i = q.front();
      for (auto j = last_visit+1; j < n_; ++j) {
        if ((*this)[i][j] && depth_[j] == -1) {
          q.push(j);
          depth_[j] = depth_[i]+1;
        }
      }
      q.pop();
      last_visit = i;
    }
  }

private:
  void init_depth()
  {
    std::fill(depth_, depth_+(n_), -1);
  }
};

int main()
{
  uint n;
  std::scanf("%u", &n);

  Graph g(n);

  uint u, k, v;
  for (auto i = 0u; i < n; ++i) {
    std::scanf("%u %u", &u, &k);
    for (auto j = 0u; j < k; ++j) {
      std::scanf("%u", &v);
      g[u-1][v-1] = 1;
    }
  }

  g.bfs();
  auto depth = g.depth();
  for (auto i = 0u; i < n; ++i) {
    std::printf("%u %d\n", i+1, depth[i]);
  }
}

// eof

C++: // ALDS1_11_C.cpp
// Graph I - BFS
#include <iostream>
#include <vector>
#include <queue>
using namespace std;

struct Vertex
{
    int id = 0;
    vector<int> adjList;
};
int tt = 0;
void bfs(vector<Vertex> &V, vector<int> &dist, int i)
{
    queue<Vertex> mq;
    mq.push(V[i]);
    dist[i] = 0;
    while(!mq.empty()) {
        Vertex tmpV = mq.front();
        mq.pop();
        for (int j = 0; j < tmpV.adjList.size(); j++) {
            int next = tmpV.adjList[j];
            if (dist[next] == -1) {
                mq.push(V[next]);
                dist[next] = dist[tmpV.id] + 1;
            }
        }
    }
}

int main()
{
    int n;
    cin >> n;
    vector<Vertex> V(n);
    vector<int> dist(n, -1);
    int id;
    int num;
    for (int i = 0; i < n; i++) {
        cin >> id >> num;
        id--;
        V[id].id = id;
        int tmp;
        for (int j = 0; j < num; j++) {
            cin >> tmp;
            tmp--;
            V[id].adjList.push_back(tmp);
        }
    }
    bfs(V, dist, 0);
    for (int i = 0; i < n; i++) {
        cout << i + 1 << " " << dist[i] << endl;
    }
    return 0;
}