Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

func stringifyArray(arr []int) string {
	return strings.TrimRight(fmt.Sprintf("%+v", arr)[1:], "]")
}

var infty = 1000000000

type nodeKey int

type DirectedGraphNode struct {
	key       nodeKey
	adjacents []*DirectedGraphNode
	visited   bool
	d         int
	parent    *DirectedGraphNode
}

type DirectedGraph struct {
	nodes []DirectedGraphNode
}

func (g *DirectedGraph) setAdjacency(l, r nodeKey) {
	g.nodes[l].adjacents = append(g.nodes[l].adjacents, &g.nodes[r])
}

func newDirectedGraph(nNodes int) *DirectedGraph {
	graph := DirectedGraph{}
	graph.nodes = make([]DirectedGraphNode, nNodes)
	for iNodes := 0; iNodes < nNodes; iNodes++ {
		graph.nodes[iNodes].key = nodeKey(iNodes)

		graph.nodes[iNodes].visited = false
		graph.nodes[iNodes].d = infty
		graph.nodes[iNodes].parent = nil
	}
	return &graph
}

type QueueEntry struct {
	node *DirectedGraphNode
	next *QueueEntry
}

type Queue struct {
	head, tail *QueueEntry
}

func (q *Queue) enqueue(node *DirectedGraphNode) {
	entry := QueueEntry{}
	entry.node = node

	if q.tail == nil {
		q.head = &entry
		q.tail = &entry
		return
	}

	q.tail.next = &entry
	q.tail = q.tail.next
}

func (q *Queue) dequeue() *QueueEntry {
	if q.head == nil {
		return nil
	}
	poped := q.head
	q.head = q.head.next
	if q.head == nil {
		q.tail = nil
	}
	return poped
}

func (q *Queue) isEmpty() bool {
	return q.head == nil
}

func fillDistancesByBreadthFirstSearch(g *DirectedGraph, startNode *DirectedGraphNode) {
	startNode.visited = true
	startNode.d = 0

	queue := Queue{}
	queue.enqueue(startNode)
	for !queue.isEmpty() {
		u := queue.dequeue().node
		for _, adjacent := range u.adjacents {
			if !adjacent.visited {
				adjacent.visited = true
				adjacent.d = u.d + 1
				adjacent.parent = u
				queue.enqueue(adjacent)
			}
		}
		u.visited = true
	}
}

func main() {
	scanner.Split(bufio.ScanWords)

	nNodes := nextInt()
	g := newDirectedGraph(nNodes + 1)

	for iNode := 0; iNode < nNodes; iNode++ {
		nodeKeyLeft := nodeKey(nextInt())
		nAdj := nextInt()
		for iAdj := 0; iAdj < nAdj; iAdj++ {
			nodeKeyRight := nodeKey(nextInt())
			g.setAdjacency(nodeKeyLeft, nodeKeyRight)
		}
	}

	// fmt.Println(g)
	fillDistancesByBreadthFirstSearch(g, &g.nodes[1])
	// fmt.Println(g)

	for iNode := 1; iNode <= nNodes; iNode++ {
		node := g.nodes[iNode]
		distance := node.d
		if distance == infty {
			distance = -1
		}
		fmt.Println(node.key, distance)
	}
}

Python: from collections import deque


def breadth_first_search(adj_matrix, n):
    distance = [0] + [-1] * (n - 1)
    searching = deque([0])
    while len(searching) > 0:
        start = searching.popleft()
        for end in range(n):
            if adj_matrix[start][end] and distance[end] == -1:
                searching.append(end)
                distance[end] = distance[start] + 1
    return distance


def main():
    n = int(input())
    adj = [[False for _ in range(n)] for _ in range(n)]
    for _ in range(n):
        ukv = input().split()
        id = int(ukv[0])
        dim = int(ukv[1])
        if dim > 0:
            nodes = map(int, ukv[2:])
            for node in nodes:
                adj[id - 1][node - 1] = True
    distance = breadth_first_search(adj, n)
    for i in range(n):
        print("{} {}".format(i + 1, distance[i]))


if __name__ == "__main__":
    main()

Python: from sys import stdin
from collections import deque
n = int(input())
d = [-1] * (n + 1)
G = [0] + [list(map(int, input().split()[2:])) for _ in range(n)]
d[1] = 0
dq = deque([1])
while len(dq) != 0:
    v = dq.popleft()
    for c in G[v]:
        if d[c] == -1 :
            d[c] = d[v] + 1
            dq.append(c)
for i, x in enumerate(d[1:], start=1):
    print(i, x)

Python: #!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
input:
4
1 2 2 4
2 1 4
3 0
4 1 3

output:
1 0
2 1
3 2
4 1
"""

import sys
from collections import deque

UNVISITED, VISITED_IN_QUEUE, POPPED_OUT = 0, 1, 2


def generate_adj_matrix(v_info):
    for v_detail in v_info:
        v_index, adj_num, *adj_list = map(int, v_detail)
        # assert len(adj_list) == adj_num
        init_adj_table[v_index].extend(adj_list)
    return init_adj_table


def graph_bfs(v_init):
    status[v_init] = VISITED_IN_QUEUE
    distance[v_init] = 0
    queue.appendleft(v_init)

    while queue:
        current = queue.popleft()
        for v in adj_table[current]:
            if status[v] is UNVISITED:
                status[v] = VISITED_IN_QUEUE
                distance[v] = distance[current] + 1
                queue.append(v)
        status[current] = POPPED_OUT
    return distance


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    vertices_num = int(_input[0])
    vertices_info = list(map(lambda x: x.split(), _input[1:]))
    init_adj_table = [[] for _ in range(vertices_num + 1)]
    # assert len(vertex_info) == vertex_num

    # config length = (vertex_num + 1)
    queue = deque()
    status = [UNVISITED] * (vertices_num + 1)
    distance = [-1] * (vertices_num + 1)

    adj_table = generate_adj_matrix(vertices_info)
    ans = graph_bfs(1)
    for j in range(vertices_num):
        print(j + 1, ans[j + 1])

Python: n = int(input())

adj = [None]
for i in range(n):
    adj_i = list(map(int, input().split()[2:]))
    adj.append(adj_i)

distance = [None] + [-1] * n

def bfs(u, d):
    pd = distance[u]
    if pd == -1 or d < pd:
        distance[u] = d
    for v in adj[u]:
        bfs(v, d + 1)


bfs(1, 0)

for i, d in enumerate(distance[1:], start=1):
    print(i, d)

Python: import queue
def s():
 N=int(input())
 M=[input().split()[2:]for _ in[0]*N]
 q=queue.Queue();q.put(0)
 d=[-1]*N;d[0]=0
 while not q.empty():
  u=q.get()
  for v in M[u]:
   v=int(v)-1
   if d[v]<0:d[v]=d[u]+1;q.put(v)
 for i in range(N):print(i+1,d[i])
if'__main__'==__name__:s()

Python: #!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
input:
4
1 2 2 4
2 1 4
3 0
4 1 3

output:
1 0
2 1
3 2
4 1
"""

import sys
from collections import deque

UNVISITED, VISITED_IN_QUEUE, POPPED_OUT = 0, 1, 2


def graph_bfs(v_init):
    queue = deque()
    status[v_init] = VISITED_IN_QUEUE
    distance[v_init] = 0
    queue.appendleft(v_init)

    while queue:
        current = queue.popleft()
        for adj in adj_table[current]:
            if status[adj] is UNVISITED:
                status[adj] = VISITED_IN_QUEUE
                distance[adj] = distance[current] + 1
                queue.append(adj)
        status[current] = POPPED_OUT
    return None


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    v_num = int(_input[0])
    vertices = list(map(lambda x: x.split(), _input[1:]))
    # assert len(vertex_info) == vertex_num

    status = [UNVISITED] * (v_num + 1)
    distance = [-1] * (v_num + 1)

    adj_table = tuple([] for _ in range(v_num + 1))
    for v_info in vertices:
        v_index, adj_num, *adj_list = map(int, v_info)
        # assert len(adj_list) == adj_num
        adj_table[v_index].extend(adj_list)

    graph_bfs(v_init=1)
    for index, v in enumerate(distance[1:], 1):
        print(index, v)

Python: #!/usr/bin/env python3
import sys
sys.setrecursionlimit(15000)
n = int(sys.stdin.readline())

ret = []
inp = sys.stdin.readlines()
G = [None]*(n+1)
depths = [-1]*(n+1)

for i in range(1,n+1):
  v = list(map(int,inp[i-1].split()))
  G[v[0]] = list(map(int,v[2:]))
#print(G)

nodes = [1]
depth = 0
while nodes:
  new = []
  for i in nodes:
    if depths[i] == -1:
      depths[i] = depth
      new += G[i]
    #print(i,nodes,depth,depths)
  depth += 1
  nodes = new

for i in range(1,n+1):
  print(i,depths[i])