Go: package main

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

type AdjacentList struct {
	matrix [][]int
}

func NewEmptyAdjacentList(dim int) *AdjacentList {
	matrix := make([][]int, dim)
	for i := 0; i < dim; i++ {
		matrix[i] = make([]int, dim)
	}
	return &AdjacentList{matrix: matrix}
}

func (al *AdjacentList) set(node int, adjacent int) {
	al.matrix[node-1][adjacent-1] = 1
}

func (al *AdjacentList) findAdjacentsFor(node int) []int {
	adjacents := []int{}
	for i, v := range al.matrix[node-1] {
		if v == 1 {
			adjacents = append(adjacents, i+1)
		}
	}
	return adjacents
}

type DistanceList struct {
	list []int
}

func NewDistanceList(dim int) *DistanceList {
	list := make([]int, dim)
	for i := 0; i < dim; i++ {
		list[i] = -1
	}
	return &DistanceList{list: list}
}

func (dl *DistanceList) set(node int, distance int) {
	dl.list[node-1] = distance
}

func (dl *DistanceList) get(node int) int {
	return dl.list[node-1]
}

func (dl *DistanceList) isVisited(node int) bool {
	return dl.list[node-1] >= 0
}

type Position struct {
	node     int
	distance int
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	dim, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	al := NewEmptyAdjacentList(dim)

	for i := 1; i <= dim; i++ {
		node, err := nextInt(sc)
		if err != nil {
			panic(err)
		}

		adjacentNum, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		for j := 0; j < adjacentNum; j++ {
			adjacent, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			al.set(node, adjacent)
		}
	}

	dl := NewDistanceList(dim)

	bfs(al, dl)

	for i := 1; i <= dim; i++ {
		fmt.Printf("%d %d\n", i, dl.get(i))
	}
}

func bfs(al *AdjacentList, dl *DistanceList) {
	stack := []Position{Position{node: 1, distance: 0}}
	for len(stack) > 0 {
		currentPosition := stack[0]
		stack = stack[1:]
		if !dl.isVisited(currentPosition.node) {
			dl.set(currentPosition.node, currentPosition.distance)
		}
		for _, v := range al.findAdjacentsFor(currentPosition.node) {
			if !dl.isVisited(v) {
				stack = append(stack, Position{node: v, distance: currentPosition.distance + 1})
			}
		}
	}
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

C++: // clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
// #define main int main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
#define stlice(from, to) substr(from, (to) - (from) + 1)
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
using namespace std;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<char> vc;
typedef vector<bool> vb;
typedef vector<string> vs;
typedef vector<pii> vpii;
typedef vector<vi> vvi;
typedef vector<vb> vvb;
typedef vector<vpii> vvpii;
const int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
const int MOD = 1000000007;
const double PI = acos(-1);
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
bool odd(const int &n) { return n & 1; }
bool even(const int &n) { return !odd(n); }
void solve();
main { solve(); return 0; }
// clang-format on

typedef int Weight;

struct Edge {
  int src, dst;
  Weight weight;
  Edge(int s, int d, Weight w)
    : src(s), dst(d), weight(w) {
  }
};

typedef vector<Edge> Edges;
typedef vector<Edges> Graph;
typedef vector<Weight> Array;
typedef vector<Array> Matrix;

void addEdge(Graph &g, int a, int b, Weight w = 1) {
  g[a].emplace_back(a, b, w);
  g[b].emplace_back(b, a, w);
}

void addArc(Graph &g, int a, int b, Weight w = 1) {
  g[a].emplace_back(a, b, w);
}

void solve() {
  int n;
  cin >> n;
  Graph g(n);
  rep(i, n) {
    int u, k;
    cin >> u >> k;
    u--;
    while (k--) {
      int v;
      cin >> v;
      v--;
      addArc(g, u, v);
    }
  }
  int c = 1;
  vi distance(n, -1);
  vi done(n);
  queue<int> q;
  distance[0] = 0;
  done[0]     = true;
  q.push(0);
  while (q.size()) {
    int x = q.front();
    q.pop();
    for (Edge e : g[x]) {
      if (done[e.dst]) continue;
      done[e.dst]     = true;
      distance[e.dst] = distance[e.src] + 1;
      q.push(e.dst);
    }
  }
  rep(i, n) {
    cout << i + 1 << ' ' << distance[i] << endl;
  }
}

C++: #include <iostream>
using namespace std;

const long N = 100;
long M[N + 1][N + 1];
long d[N + 1];
long n;
const long INFTY = 101;

long solve(long id, long dist){
	if (id == 1) d[1] = 0;
	for (long i = 2; i <= n; i++){
		if (M[id][i]){
			if (dist + 1 < d[i]){
				d[i] = dist + 1;
				solve(i, dist + 1);
			} 
		}
	}
}

int main(){
	cin >> n;
	for (long i = 1; i <= n; i++){
		d[i] = INFTY;
		for (long j = 1; j <= n; j++){
			M[i][j] = 0;
		}
	}
	for (long i = 0; i < n; i++){
		long v, k;
		cin >> v >> k;
		for (long j = 0; j < k; j++){
			long nh;
			cin >> nh;
			M[v][nh] = 1;
		}
	}
	solve(1, 0);
	for (long i = 1; i <= n; i++){
		if (d[i] == INFTY) d[i] = -1;
		cout << i << " " << d[i] << endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;

typedef pair<int, int> P;
typedef long long int LL;

vector<int> v[101];
vector<int> dist;
queue<int> q;

int bfs() {
    dist[1] = 0;
    q.push(1);

    while (!q.empty()) {
        int c = q.front();
        q.pop();
        for (int i = 0; i < v[c].size(); i++) {
            if (dist[v[c][i]] == -1) {
                dist[v[c][i]] = dist[c] + 1;
                q.push(v[c][i]);
            }
        }
    }
}

int main() {
    int n;
    cin >> n;
    dist.resize(n + 1, -1);

    for (int i = 0; i < n; i++) {
        int u, k;
        cin >> u >> k;
        for (int j = 0; j < k; j++) {
            int a;
            cin >> a;
            v[u].push_back(a);
            v[a].push_back(u);
        }
    }

    bfs();

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

    return 0;
}

C++: //1933-
#include<iostream>
#include<cstdio>
#include<string>
#include<algorithm>
#include<cstring>
#include<vector>
#include<queue>
using namespace std;
#define INT(x) int x; scanf("%d",&x)
#define INPUT(x) scanf("%d",&x)
#define REP1(x,n) for(int x = 0; x < n; x++)
#define REP2(x,s,e) for(int x = s; x <= e; x++)
#define BR printf("\n")
#define INF 2000000000
#define FIND 1
#define END 2

vector<int> V[100];
priority_queue<pair<int,int> > PQ;//distance,id
int d[100];
int StateNode[100] = {};

void BFS(pair<int,int> p){
    if(d[p.second] <= -p.first) {
        PQ.pop();
        if(!PQ.empty()) BFS(PQ.top());
        return;
    }
    d[p.second] = -p.first;
    PQ.pop();
    
    REP1(k,V[p.second].size()){
        if (StateNode[V[p.second][k]] == 0 || (StateNode[V[p.second][k]] == FIND && -p.first+1)) {
            PQ.push(make_pair(p.first-1,V[p.second][k]));
            StateNode[V[p.second][k]] = FIND;
        }
    }
    
    if(!PQ.empty()) BFS(PQ.top());
}

int main(){
    INT(N);
    REP1(i,N){
        int from,n;
        scanf("%d %d",&from,&n);
        REP1(j,n){
            INT(to);
            V[i].push_back(to-1);
        }
        d[i] = INF;
    }
    
    PQ.push(make_pair(0,0));
    BFS(PQ.top());
    
    REP1(i,N){
        printf("%d %d\n",i+1,d[i]);
    }
    
    return 0;
}