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 <bits/stdc++.h>
using namespace std;

#define rep(i, n) for (int i = 0; i < n; ++i)
#define ALL(a) (a).begin(), (a).end()

template <class T>
inline bool chmin(T &a, T b)
{
  if (a > b)
  {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T &a, T b)
{
  if (a < b)
  {
    a = b;
    return true;
  }
  return false;
}

using ll = long long;
using ld = long double;
using P = pair<int, int>;
using DoP = pair<double, double>;
using edge = struct { int to; ll cost; }; // edge x = {to, cost}

const int di[] = {0, 1, 0, -1, 1, 1, -1, -1};
const int dj[] = {1, 0, -1, 0, 1, -1, 1, -1};
const int INF = INT_MAX;
const ll INF64 = 1ll << 40;
const int mod = 1000000007;

struct Sieve
{
  int n;
  vector<int> f, primes;
  Sieve(int n = 1) : n(n), f(n + 1)
  {
    f[0] = f[1] = -1;
    for (ll i = 2; i <= n; ++i)
    {
      if (f[i])
        continue;
      primes.push_back(i);
      f[i] = i;
      for (ll j = i * i; j <= n; j += i)
      {
        if (!f[j])
          f[j] = i;
      }
    }
  }
  bool isPrime(int x) { return f[x] == x; }
  vector<int> factorList(int x)
  {
    vector<int> res;
    while (x != 1)
    {
      res.push_back(f[x]);
      x /= f[x];
    }
    return res;
  }
  vector<P> factor(int x)
  {
    vector<int> fl = factorList(x);
    if (fl.size() == 0)
      return {};
    vector<P> res(1, P(fl[0], 0));
    for (int p : fl)
    {
      if (res.back().first == p)
      {
        res.back().second++;
      }
      else
      {
        res.emplace_back(p, 1);
      }
    }
    return res;
  }
};
struct UnionFind
{
  vector<int> par;
  vector<int> siz;
  UnionFind(int N) : par(N), siz(N, 1) {for (int i = 0; i < N; i++) par[i] = i;}
  
  void init(int N) {
    siz.assign(N, 1);
    par.resize(N);
    for(int i = 0; i < N; ++i) par[i] = i;
  }

  int root(int x) {
    while(par[x] != x) {x = par[x] = par[par[x]];}
    return x;
  }

  bool unite(int x, int y)
  {
    x = root(x);
    y = root(y);
    if(x == y) return false;

    if(siz[x] < siz[y]) swap(x, y);
    siz[x] += siz[y];
    par[y] = x;
    return true;

  }

  bool isSame(int x, int y) {return root(x) == root(y); }

  int size(int x) { return siz[root(x)]; }
};
struct mint
{
  ll x; // typedef long long ll;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint a)
  {
    if ((x += a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator-=(const mint a)
  {
    if ((x += mod - a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator*=(const mint a)
  {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const
  {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const
  {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const
  {
    mint res(*this);
    return res *= a;
  }
  mint pow(ll t) const
  {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const
  {
    return pow(mod - 2);
  }
  mint &operator/=(const mint a)
  {
    return (*this) *= a.inv();
  }
  mint operator/(const mint a) const
  {
    mint res(*this);
    return res /= a;
  }
};
// h(n, r) = c(n+r-1, r)
struct combination
{
  vector<mint> fact, ifact;
  combination(int n) : fact(n + 1), ifact(n + 1)
  {
    assert(n < mod);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i)
      ifact[i - 1] = ifact[i] * i;
  }
  mint operator()(int n, int k)
  {
    if (k < 0 || k > n)
      return 0;
    return fact[n] * ifact[k] * ifact[n - k];
  }
};

ll modpow(ll a, ll n) {
  ll res = 1;
  while (n > 0) {
      if (n & 1) res = res * a % mod;
      a = a * a % mod;
      n >>= 1;
  }
  return res;
}

int main(){
  int n;
  cin >> n;
  vector<vector<int>> e(n+1);
  rep(i, n) {
    int u, k;
    cin >> u >> k;
    rep(j, k) {
      int v;
      cin >> v;
      e[u].push_back(v);
    }
  }
  vector<int> ans(n+1, -1);
  queue<int> q;
  auto update = [&](int now) {
    for(auto next : e[now]) {
      if(ans[next] == -1) {
        ans[next] = ans[now]+1;
        q.push(next);
      }
    }
  };
  ans[1] = 0;
  q.push(1);
  while(!q.empty()) {
    auto now = q.front(); q.pop();
    update(now);
  }
  rep(i, n) cout << i+1 << " " << ans[i+1] << endl;
}

C++: #include <stdio.h>
#define N 100
#define INF 100000000

int G[N+1][N+1], vis[N+1], n, size[N+1];

void dfs(int p, int t){
  int i;
  vis[p] = t;
  for(i=1;i<=size[p];i++) if(t + 1 < vis[G[p][i]]) dfs(G[p][i], t + 1);
}

main(){
  int i, j, u;
  scanf("%d", &n);
  for(i=1;i<=n;i++){
    vis[i] = INF;
    scanf("%d", &u);
    scanf("%d", &size[u]);
    for(j=1;j<=size[u];j++) scanf("%d", &G[u][j]);
  }
  dfs(1, 0);
  for(i=1;i<=n;i++) printf("%d %d\n", i, (vis[i] == INF) ? -1 : vis[i]);
  return 0;
}

C++: #include <iostream>
#include <stdio.h>
#include <vector>
#include <utility>
#include <string>
#include <algorithm>
#include <cmath>
#include <queue>
#include <cstring>
 
typedef long long ll;

#define rep(i,n) for(ll i = 0; i < n; i++)
 
using namespace std;
 
const ll INF = ll(1e18)+1;
const double PI=3.14159265358979323846;

vector<vector<int> > G(105);
vector<int> D(105,-1);

int main(){
  int n;
  cin >> n;
  rep(i,n){
    int u,k;
    cin >> u >> k;
    rep(j,k){
      int v;
      cin >> v;
      G[u].push_back(v);
    }
  }

  queue<int> q;
  q.push(1);
  D[1] = 0;  
  while( !q.empty() ){
    int v = q.front();
    q.pop();
    
    rep(i,G[v].size()){      
      if(D[G[v][i]] != -1) continue;
      D[G[v][i]] = D[v] + 1;
      q.push(G[v][i]);
    }
  }

  rep(i,n){
    cout << i+1 << " " << D[i+1] << endl;
  }
}