Go: package main

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

//util
var sc = bufio.NewScanner(os.Stdin)

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

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func printList(list []int) {
	n := len(list)
	buf := bufio.NewWriter(os.Stdout)
	for _, v := range list[0 : n-1] {
		buf.Write([]byte(fmt.Sprintf("%d ", v)))
	}
	buf.Write([]byte(fmt.Sprintf("%d\n", list[n-1])))
	buf.Flush()
}

func max(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func min(a, b int) int {
	if a > b {
		return b
	} else {
		return a
	}
}

//solve
const INFTY = (1 << 21)
const MAX = 100
const WHITE = 0
const GRAY = 1
const BLACK = 2

var time, n int

//隣接行列
var M [MAX][MAX]int

//d[i]: 頂点1から頂点iまでの距離
var color, d [MAX]int

func bfs(s int) {
	var q []int
	q = append(q, s)
	for i := 0; i < n; i++ {
		d[i] = INFTY
	}
	//sは開始点なので、0をいれる
	d[s] = 0

	//キューが空になるまで、以下を繰り返す
	for len(q) > 0 {
		u := q[0]
		q = q[1:]
		for v := 0; v < n; v++ {
			if M[u][v] == 0 {
				continue
			}
			if d[v] != INFTY {
				continue
			}
			d[v] = d[u] + 1
			q = append(q, v)
		}
	}

	for i := 0; i < n; i++ {
		fmt.Printf("%d ", i+1)
		if d[i] == INFTY {
			fmt.Printf("%d\n", -1)
		} else {
			fmt.Printf("%d\n", d[i])
		}
	}
}

func main() {
	sc.Split(bufio.ScanWords)
	n = nextInt()
	for i := 0; i < n; i++ {
		u, k := nextInt(), nextInt()
		M[u-1][u-1] = 0

		//fmt.Println(u, k)
		if k > 0 {
			for j := 0; j < k; j++ {

				v := nextInt()
				M[u-1][v-1] = 1

			}
		}

	}

	bfs(0)

}

C++: #include<iostream>
#include<vector>

int ptod[101]{};
int vertices_num;
std::vector<int> dest[101];
std::vector<int> visited_list;
void search();

int main()
{
	int vertex_tmp, dest_num, dest_tmp;

	std::cin >> vertices_num;
	for (int i = 1; i <= vertices_num; ++i)
	{
		std::cin >> vertex_tmp >> dest_num;
		for (int j = 0; j < dest_num; ++j)
		{
			std::cin >> dest_tmp;
			dest[vertex_tmp].push_back(dest_tmp);
		}
	}

	search();

	for (int i = 1; i <= vertices_num; ++i)
		std::cout << i << " " << ptod[i] << std::endl;

	return 0;
}

void search()
{
	int pre_size{ 0 };
	visited_list.push_back(1);
	bool visited[101]{ false, true };
	for (int i = 1; pre_size != visited_list.size(); ++i)
	{
		int now_size = visited_list.size();
		for (int j = pre_size; j < now_size; ++j)
			for (auto e : dest[visited_list[j]])
				if (!visited[e])
				{
					visited[e] = true;
					visited_list.push_back(e);
					ptod[e] = i;
				}
		pre_size = now_size;
	}
	for (int i = 1; i <= vertices_num; ++i)
		if (!visited[i])
			ptod[i] = -1;
	return;
}

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

int n;
vector < int > G[105];
int mc[105];

void bfs()
{
    queue < int > que;

    fill_n(mc, 105, -1);
    que.push(1);
    mc[1] = 0;
    
    while ( !que.empty() ) {
        int u = que.front(); que.pop();
        for ( auto &v : G[u] ) {
            if ( mc[v] == -1 ) {
                mc[v] = mc[u] + 1;
                que.push(v);
            }
        }
    }
}

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

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

    return (0);
}