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 <stdio.h>
#include <string.h>
#include<iostream>
#include<queue>
using namespace std;

char s[13][1];
int D[102][102];
int A[103],f[103],w,h,n,sx,sy,gx,gy,e,g[103];
int   kensa(int ,int);
int main(){
	queue<int> P;
	int i,j,a,b,c,d;
	for(i=0;i<100;i++){
		for(j=0;j<100;j++){
			D[i][j]=-1;		
		}					
	}						
	for(i=0;i<100;i++){		
		A[i]=0;				
		f[i]=-1;
		g[i]=0;
	}							
	scanf("%d" ,&a);//     a=4
	for(i=1;i<=a;i++){
        scanf("%d",&b);		//
		scanf("%d",&b);			//b=2					//
		for(j=1;j<=b;j++){		//
		scanf("%d",&c);			//					//
		D[i][c]=1;
//
		}						//D[???][???]
	}				
	for(i=1;i<=a;i++){
		for(j=1;j<=a;j++){
		//	printf("%d %d %d\n",i,j,D[i][j]);
		}	
	}//
	P.push(1);
	//P???1
	f[1]=0;
	while(!P.empty()){			//
		d=P.front();
		//
		A[d]=1;
		//
		P.pop();				//
		for(i=1;i<=a;i++){
			//printf("%d %d %d\n",d,i,D[d][i]);//
			if(D[d][i]==-1){		//
			continue;			//
			}					//
			if(A[i]==1){		//
			continue;			//
			}					//
			P.push(i);			//
			f[i]=g[d]+1;
			g[i]=g[d]+1;
			A[i]=1;
			//printf("%d\n",P.back());
		}	
	}							//
	for(i=1;i<=a;i++){			//
	printf("%d %d\n",i, f[i]);	//
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = s; i < (int)(n); i++)
#define rep3(i, s, n) for (int i = s; i > (int)(n); i--)
#define all(obj) obj.begin(), obj.end()
#define db(x) cerr << #x << ":" << x << " "
#define dbl(x) cerr << #x << ":" << x << "\n"
#define dbv(vec) cerr << #vec << ":"; for (auto e : vec) cerr << e << " "; cout << "\n"
#define dbvv(vv) cerr << #vv << ":\n"; for (auto vec : vv) { for (auto e : vec) cerr << e << " "; cerr << "\n"; }
#define dbm(map) cerr << #map << ":"; for (auto p : map) cerr << "(" << p.first << ", " << p.second << "), "; cerr << "\n";
#define YN(f) cout << (f ? "YES" : "NO") << "\n"
#define Yn(f) cout << (f ? "Yes" : "No") << "\n"
#define yn(f) cout << (f ? "yes" : "no") << "\n"
using ll = long long;
using vi = vector<int>; using vl = vector<ll>; using vs = vector<string>; using vb = vector<bool>;
using vvi = vector<vi>; using vvl = vector<vl>; using vvb = vector<vb>;
using pii = pair<int, int>; using pll = pair<ll, ll>;
using vpii = vector<pii>; using vpll = vector<pll>;
using ti3 = tuple<int, int, int>; using tl3 = tuple<ll, ll, ll>;
using mii = map<int, int>; using mil = map<int, ll>; using mli = map<ll, int>; using mll = map<ll, ll>;

int main() {
	int n; cin >> n;
	vvi g(n + 1); vi d(n + 1, -1); // 1-ind
	rep2(i, 1, n + 1) {
		int _, k; cin >> _ >> k;
		rep(j, k) {
			int v; cin >> v;
			g[i].push_back(v);
		}
	}
	// dbvv(g);
	queue<int> q;
	q.push(1); d[1] = 0;
	while (!q.empty()) {
		int u = q.front(); q.pop();
		for (int v : g[u]) {
			if (d[v] != -1) continue;
			d[v] = d[u] + 1;
			q.push(v);
		}
	}
	rep2(i, 1, n + 1) printf("%d %d\n", i, d[i]);
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <cmath>
#include <deque>
#include <iterator>
#include <map>
#include <queue>
#include <string>
#include <tuple>
#include <utility>
using namespace std;

using ll=long long;
template<class T> using V = vector<T>;
template<class T, class U> using P = pair<T, U>;
using vll = V<ll>;
using vvll = V<vll>;
#define rep(i, k, n) for (ll i=k; i<(ll)n; ++i)
#define REP(i, n) rep(i, 0, n)
template<class T> inline bool chmax(T& a, T b) {if (a<b) {a=b; return true;} return false;}
template<class T> inline bool chmin(T& a, T b) {if (a>b) {a=b; return true;} return false;}

int main() {
  ll n; cin >> n;
  vvll edges(n, vll());
  REP(i, n) {
    ll u, k; cin >> u >> k;
    REP(j, k) {
      ll to; cin >> to;
      edges.at(u-1).push_back(to-1);
    }
  }
  vll d(n, -1);
  V<bool> visited(n, false);
  queue<ll> q; q.push(0);
  ll tmpd = 0;
  while (!q.empty()) {
    queue<ll> tmpq;
    while (!q.empty()) {
      ll to = q.front(); q.pop();
      if (visited.at(to)) continue;
      visited.at(to) = true; d.at(to) = tmpd;
      REP(i, edges.at(to).size()) {
        if (visited.at(edges.at(to).at(i))) continue;
        tmpq.push(edges.at(to).at(i));
      }
    }
    q = tmpq; tmpd++;
  }
  REP(i, n) cout << i+1 << ' ' << d.at(i) << endl;
  return 0;
}