Go: package main

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

func main() {
	scn := bufio.NewScanner(os.Stdin)
	scn.Split(bufio.ScanWords)
	nextInt := func() int { scn.Scan(); r, _ := strconv.Atoi(scn.Text()); return r }
	w := bufio.NewWriter(os.Stdout)

	n := nextInt()
	vecs := make([][]int, n)
	for i := 0; i < n; i++ {
		u := nextInt()
		k := nextInt()
		for j := 0; j < k; j++ {
			vecs[u-1] = append(vecs[u-1], nextInt()-1)
		}
	}

	ds := make([]int, 0, n)
	for i := 0; i < n; i++ {
		ds = append(ds, -1)
	}

	q := make([]int, 0, n)
	q = append(q, 0)
	ds[0] = 0

	for len(q) > 0 {
		i := pop(&q)
		for _, v := range vecs[i] {
			if ds[v] == -1 {
				ds[v] = ds[i]+1
				q = append(q, v)
			}
		}
	}

	for i, d := range ds {
		fmt.Fprintln(w, i+1, d)
	}

	w.Flush()
}

func pop(q *[]int) int {
	v := (*q)[0]
	*q = (*q)[1:]
	return v
}

C++: #include <bits/stdc++.h>
#define REP(i, n) for(int i = 0; i < (n); i++)
#define REP1(i, n) for(int i = 1; i <= (n); i++)
#define REPD(i,a,b) for (int i=(a);i<(b);i++)
#define ALL(v) (v).begin(), (v).end()
using namespace std;
typedef long long ll;
typedef vector<string> vs;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef set<int> si;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef pair<int, int> pi;
typedef queue<int> qi;
typedef queue<pi> qpi;
typedef pair<ll, ll> pll;
typedef queue<pll> qpll;
typedef vector<pi> vpi;
typedef vector<pll> vpll;
const int mod = 1000000007;
const int INF = 1001001001;
// 小数点　<< fixed << setprecision(0) <<
// sort降順　sort(ALL(),greater<int>());
// 円周率　M_PI
// 文字判定　isupper islower
// 順列　do {} while(next_permutation(ALL(X)));
// 最大値　LLONG_MAX
// a内でx以上　auto iter = lower_bound(ALL(a), x);
// a内でxより大きい　auto iter = upper_bound(ALL(a), x);
int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
int dy[8] = {0, 1, 0, -1, 1, -1, 1, -1};
struct edge {
    int from; //出発点
    int to;   //到達点
    int cost; //移動コスト
};
typedef struct edge se;
typedef vector<edge> ve;
unsigned euclidean_gcd(unsigned a, unsigned b) {
  if(a < b) return euclidean_gcd(b, a);
  unsigned r;
  while ((r=a%b)) {
    a = b;
    b = r;
  }
  return b;
}

int main() {
  int n;
  cin >> n;
  vvi tree(n);
  REP(i,n) {
    int u,k;
    cin >> u >> k;
    REP(j,k) {
      int v;
      cin >> v;
      tree[i].push_back(v-1);
    }
  }
  qi que;
  vi check(n,-1);
  que.push(0);
  check[0]=0;
  while(!que.empty()) {
    int x=que.front();
    int cnt=check[x];
    que.pop();
    for(auto i:tree[x]) {
      if(check[i]!=-1) continue;
      check[i]=cnt+1;
      que.push(i);
    }
  }
  REP(i,n) {
    cout << i+1 << " " << check[i] << endl;
  }
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
 
using ll = long long;
using ld = long double;
#define FOR(i, m, n) for (int i = (m); i < (n); i++)
#define FORR(i, m, n) for (int i = (m); i >= (n); i--)
#define REP(i, n) FOR(i, 0, (n))
#define REPR(i, n) FORR(i, (n) - 1, 0)
#define REP1(i, n) FOR(i, 1, (n) + 1)
#define REPS(c, s) for (char c : s)
#define ALL(c) (c).begin(), (c).end()
#define SORT(c) sort(ALL(c))
#define REV(c) reverse(ALL(c))
#define sz(v) (int)v.size()
#define endl '\n'
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;}
template<class T> inline void printv(vector<T>& v) {int n = sz(v); REP(i, n) cout << v[i] << (i == n - 1 ? endl : ' ');}
const int MOD = 1000000007;
const int INF = 1000000001;
const ll LINF = 1000000001000000001LL;
 
void solve();
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(numeric_limits<double>::max_digits10);
    solve();
    return 0;
}

void solve() {
    int n;
    cin >> n;
    vector<vector<int>> g(n, vector<int>());
    int u, k;
    REP(i, n) {
        cin >> u >> k;
        u--;
        int v;
        REP(j, k) {
            cin >> v;
            v--;
            g[u].emplace_back(v);
        }
    }

    deque<pair<int, int>> q;
    q.emplace_back(0, 0);

    vector<int> ans(n, -1);
    while (!q.empty()) {
        auto p = q.front(); q.pop_front();
        if (ans[p.first] == -1) ans[p.first] = p.second;

        for (auto r : g[p.first]) {
            if (ans[r] != -1) continue;
            q.emplace_back(r, p.second + 1);
        }
    }
    REP(i, n) cout << i + 1 << " " << ans[i] << endl;
}

C++: #include <iostream>
#include <queue>
using namespace std;
int n,G[101][101];
int d[101];
int dis;
void bfs(){
    queue<int>q;
    int u=1;
    q.push(u);
    d[u]=dis;
    while(!q.empty()){
        u=q.front();
        dis=d[u]+1;
        for(int i=1;i<=n;i++)
        {
            if(G[u][i]==1 && d[i]==-1)
            {
                q.push(i);
                d[i]=dis;
            }
        }
        q.pop();
    }
}
int main()
{
    int u,k,v;
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        d[i]=-1;
        for(int j=1;j<=n;j++)
            G[i][j]=0;
    }
    for(int i=0;i<n;i++)
    {
        cin>>u>>k;
        for(int j=0;j<k;j++)
        {
            cin>>v;
            G[u][v]=1;
        }
    }
    dis=0;
    bfs();
    for(int i=1;i<=n;i++)
        cout<<i<<' '<<d[i]<<endl;
    return 0;
}

C++: //16D8103013E Sen Shunkou
#include<iostream>
#include<queue>
int n;
int cnt=0;

int main(){
    //input
    int n;
    std::cin>>n;

    int cnt=0;
    int A[100][100];
    int dis_min[n];
    bool visited[n];

    for(int i=0;i<100;i++){
        for(int j=0;j<100;j++){
            A[i][j]=0;
        }
    }

    for(int i=0;i<n;i++){
        std::cin>>A[i][0];
        std::cin>>A[i][1];
        for(int j=0;j<A[i][1];j++){
            std::cin>>A[i][j+2];
        }
    }

    for(int i=0;i<n;i++){
        dis_min[i]=-1;
    }

    //initialization
    std::queue<int> que;
    que.push(0);
    //std::cout<<"\n"<<que.front()<<"\n";
    //std::cout<<que.size()<<"\n\n";

    while(!que.empty()){
        int q=que.size();
        for(int k=0;k<q;k++){
            //std::cout<<"quesize"<<que.size()<<"\n";
            int i=que.front();
            que.pop();
            visited[i]=true;
            dis_min[i]=cnt;
            //std::cout<<i<<"cnt"<<cnt<<"\n";
            if(A[i][1]!=0){
                for(int j=0;j<A[i][1];j++){
                    if(visited[A[i][j+2]-1]!=true){
                        visited[A[i][j+2]-1]=true;
                        que.push(A[i][j+2]-1);
                        //std::cout<<A[i][j+2]-1<<"\n";
                    }
                }
            }
        }
        cnt++;
        //std::cout<<"cnt="<<cnt<<"\n";
    }

    //std::cout<<"===========\n";

    //output
    for(int i=0;i<n;i++){
        std::cout<<i+1<<" "<<dis_min[i]<<std::endl;
    }

    return 0;
}

C++: /**
 * Bredth first search.
 * graphs could be circular.
 */

#include <iostream>
using namespace std;
const int N = 101;
int adj[N][N] = {0};
int d[N] = {0};
int s[N] = {0};

void bfs(int n, int dd) {
	int k = adj[n][0];
	int kk = 0;
	for (int j=1;j<=k;j++) {
		int nn = adj[n][j];
		if (d[nn] != -1) continue;
		d[nn]=dd;
		s[kk++]=nn;
	}

	for (int j=0;j<kk;j++)
	{
		bfs(s[j], dd+1);
	}
}

int main()
{
	int n;
	cin >> n;
	for (int i=1;i<=n;i++){
		int j, k;
		cin >> j >> k;
		d[j]=-1;
		adj[j][0]=k;
		for (int m=1;m<=k;m++) {
			int a;
			cin >> a;
			adj[j][m]=a;
		}
	}

	d[1]=0;

	bfs(1, 1);

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

	return 0;
}