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))
}

Python: from collections import deque
n = int(input())
M = [[0]*n for _ in range(n)]
d = [-1]*n
st = [0]*n
for _ in range(n):
    i = [int(i) for i in input().split()]
    u = i[0]
    k = i[1]
    V = i[2:]
    for v in V: M[u-1][v-1] = 1

def bfs(s):
    Q = deque()
    Q.append(s)
    st[s] = 1
    d[s] = 0
    while Q:
        u = Q.popleft()
        for v in range(n):
            if M[u][v] and st[v] == 0:
                st[v] = 1
                Q.append(v)
                d[v] = d[u]+1
        st[u] = 2
    return

bfs(0)
for i in range(n): print(i+1,d[i])

Python: from collections import deque

n = int(input())

adj = [0]*n # adjacent list
d = [-1]*n # distance from the source vertex
c = ['w']*n # the 'color' of each vertex

# receiving input (the structure of the graph)
for i in range(n):
    tmp = list(map( int, input().split() ) )
    adj[tmp[0]-1] = list(map(lambda x : x - 1, tmp[2:]))

# set the source vertex
s = 0
d[s] = 0
c[s] = 'g'


Q = deque()
Q.append(s)

while Q:
    u = Q.popleft()
    for v in adj[u]:
        if c[v] == 'w':
            c[v] = 'g'
            d[v] = d[u] + 1
            Q.append(v)
    c[u] = 'b'
    

for i in range(n):
    print(f'{i+1} {d[i]}')

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

Python: def BFS(G):
    ans = [0] + [[i+1,-1] for i in range(len(G))]
    def main(G,i,d):
        ans[i] = [i, d]
        for j in G[i-1][2:]: main(G,j,d+1)
    main(G,1,0)
    return ans[1:]


if __name__=='__main__':
    n = int(input())
    G = [list(map(int,input().split())) for _ in range(n)]
    for out in BFS(G): print(*out)

Python: n = int(input())
G = [[0]]+[list(map(int, input().split()))[2:] for _ in range(n)]
# print(G)
from collections import deque
d = deque([1])
dist  = [10**10 for _ in range(n+1)]
dist[1] = 0
while len(d) != 0:
    now = d.popleft()
    # print(now)
    for nexte in G[now]:
        if dist[now] +1 < dist[nexte]:
            dist[nexte] = dist[now] + 1
            d.append(nexte)
for i,d in enumerate(dist[1:]):
    if d != 10**10:
        print(i+1,d)
    else:
        print(i+1,-1)

Python: from collections import deque

def bfs(adj_mat, d):
    Q = deque()
    N = len(d)
    color = ["W" for n in range(N)]

    Q.append(0)
    d[0] = 0

    while len(Q) != 0:
        u = Q.popleft()

        for i in range(N):
            if adj_mat[u][i] == 1 and color[i] == "W":
                color[i] = "G"
                d[i] = d[u] + 1
                Q.append(i)

        color[u] = "B"

    for i in range(N):
        if color[i] != "B":
            d[i] = -1

def Main():
    N = int(input())

    adj_mat = [[0 for n in range(N)] for n in range(N)]
    d = [0] * N

    for n in range(N):
        u, k , *V = map(int, input().split())

        if k > 0:
            for i in V:
                adj_mat[n][i - 1] = 1

    bfs(adj_mat, d)

    for n in range(N):
        print("{} {}".format(n + 1, d[n]))
Main()

Python: if __name__ == '__main__':
    from sys import stdin
    input = stdin.readline

    from collections import deque, defaultdict
    from copy import deepcopy

    INFTY = -1   # 探索しなかったやつを-1としてprintしやすくするために-1とした。

    n = int(input())

    M = [[0]*n for _ in range(n)]

    def bfs(s):
        q = deque()
        q.append(s)
        d = [INFTY]*n
        d[s] = 0
        while q: # qが空だとwhileループから抜ける
            u = q.popleft()  # pythonのdequeはpopleft関数で戻り値がpopした要素になる
            for v in range(n):
                if M[u][v] == 0:
                    continue
                if d[v] != INFTY:
                    continue
                d[v] = d[u] + 1
                q.append(v)
        for i in range(n):
            print(str(i+1) + ' ' + str(d[i]))

    for _ in range(n):
        u, k, *vv = map(int, input().split())
        u -= 1
        for v in vv:
            v -= 1
            M[u][v] = 1

    bfs(0)

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