Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

func stringifyArray(arr []int) string {
	return strings.TrimRight(fmt.Sprintf("%+v", arr)[1:], "]")
}

var infty = 1000000000

type nodeKey int

type DirectedGraphNode struct {
	key       nodeKey
	adjacents []*DirectedGraphNode
	visited   bool
	d         int
	parent    *DirectedGraphNode
}

type DirectedGraph struct {
	nodes []DirectedGraphNode
}

func (g *DirectedGraph) setAdjacency(l, r nodeKey) {
	g.nodes[l].adjacents = append(g.nodes[l].adjacents, &g.nodes[r])
}

func newDirectedGraph(nNodes int) *DirectedGraph {
	graph := DirectedGraph{}
	graph.nodes = make([]DirectedGraphNode, nNodes)
	for iNodes := 0; iNodes < nNodes; iNodes++ {
		graph.nodes[iNodes].key = nodeKey(iNodes)

		graph.nodes[iNodes].visited = false
		graph.nodes[iNodes].d = infty
		graph.nodes[iNodes].parent = nil
	}
	return &graph
}

type QueueEntry struct {
	node *DirectedGraphNode
	next *QueueEntry
}

type Queue struct {
	head, tail *QueueEntry
}

func (q *Queue) enqueue(node *DirectedGraphNode) {
	entry := QueueEntry{}
	entry.node = node

	if q.tail == nil {
		q.head = &entry
		q.tail = &entry
		return
	}

	q.tail.next = &entry
	q.tail = q.tail.next
}

func (q *Queue) dequeue() *QueueEntry {
	if q.head == nil {
		return nil
	}
	poped := q.head
	q.head = q.head.next
	if q.head == nil {
		q.tail = nil
	}
	return poped
}

func (q *Queue) isEmpty() bool {
	return q.head == nil
}

func fillDistancesByBreadthFirstSearch(g *DirectedGraph, startNode *DirectedGraphNode) {
	startNode.visited = true
	startNode.d = 0

	queue := Queue{}
	queue.enqueue(startNode)
	for !queue.isEmpty() {
		u := queue.dequeue().node
		for _, adjacent := range u.adjacents {
			if !adjacent.visited {
				adjacent.visited = true
				adjacent.d = u.d + 1
				adjacent.parent = u
				queue.enqueue(adjacent)
			}
		}
		u.visited = true
	}
}

func main() {
	scanner.Split(bufio.ScanWords)

	nNodes := nextInt()
	g := newDirectedGraph(nNodes + 1)

	for iNode := 0; iNode < nNodes; iNode++ {
		nodeKeyLeft := nodeKey(nextInt())
		nAdj := nextInt()
		for iAdj := 0; iAdj < nAdj; iAdj++ {
			nodeKeyRight := nodeKey(nextInt())
			g.setAdjacency(nodeKeyLeft, nodeKeyRight)
		}
	}

	// fmt.Println(g)
	fillDistancesByBreadthFirstSearch(g, &g.nodes[1])
	// fmt.Println(g)

	for iNode := 1; iNode <= nNodes; iNode++ {
		node := g.nodes[iNode]
		distance := node.d
		if distance == infty {
			distance = -1
		}
		fmt.Println(node.key, distance)
	}
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#include<list>
#include<string>
#include<cstring>
#include<cstdlib>
#include<cstdio>
#include<cmath>
using namespace std;

const int NIL = -1;
const int MAX = 20001;

int G[101][101];
int color[101], d[101];
int t = 0;

int main(void)
{
	int n, k, v, u;
	queue<int>Q;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> u >> k;
		for (int i = 0; i < k; i++) {
			cin >> v;
			G[u][v] = 1;
		}
	}
	for (int i = 1; i <= n; i++)
		d[i] = MAX;
	color[1] = 1;
	d[1] = 0;
	Q.push(1);
	while (Q.size()) {
		u = Q.front();
		Q.pop();
		for (int v = 1; v <= n; v++) {
			if (G[u][v] && color[v] == 0) {
				color[v] = 1;
				d[v] = d[u] + 1;
				Q.push(v);
			}
		}
		color[u] = 2;
	}
	for (int i = 1; i <= n; i++) {
		if (d[i] == MAX)
			d[i] = -1;
	}
	for (int i = 1; i <= n; i++) {
		cout << i << " " << d[i] << endl;
	}
	return 0;
}

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

char s[13][1];
int D[102][102];
int A[100],f[100],w,h,n,sx,sy,gx,gy,e,g[100];
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>
typedef long long ll;
using namespace std;
ll MOD = 1000000007;

#define vec                vector<int>
#define vecll              vector<ll>
#define vecd               vector<double>
#define vecst              vector<string>
#define vecb               vector<bool>
#define vec2(var, n, m)    vector<vector<int>> var(n, vector<int>(m, 0))
#define vecll2(var, n, m)  vector<vector<ll>> var(n, vector<ll>(m, 0))

#define rep(i,n)         for(ll i=(ll)0; i<(ll)n; i++)
#define REP(i,m,n)       for(ll i=(ll)m; i<(ll)n; i++)
#define arr(var, n)      vec var(n); rep(i,n){cin >> var[i];}
#define arrll(var, n)    vecll var(n); rep(i,n){cin >> var[i];}
#define arrst(var, n)    vecst var(n); rep(i,n){cin >> var[i];}
#define all(var)         (var).begin(), (var).end()
#define sortall(var)     sort(all(var))
#define uniqueall(v)     v.erase(unique(v.begin(), v.end()), v.end());
#define f_sum(var)       accumulate(all(var), 0)
#define f_sumll(var)     accumulate(all(var), 0LL)
#define chmin(v1, v2)    v1 = min(v1, v2)
#define chmax(v1, v2)    v1 = max(v1, v2)
#define pb(var)          push_back(var)
#define prt(var)         cout << (var) << "\n"
#define prtd(n, var)     cout << fixed << setprecision(n) << (var) << "\n"
#define prtfill(n, var)  cout << setw(n) << setfill('0') << (var);
#define prt2(v1, v2)     cout << (v1) << " " << (v2) << "\n"
#define prt3(v1, v2, v3) cout << (v1) << " " << (v2) << " " << (v3) << "\n"
#define prtall(v)        rep(i,v.size()){cout<<v[i]<<(i!=v.size()-1?" ":"\n");}
void prtok(bool ok){prt(ok ? "yes" : "no");}
//----------------------------------------------------------------
class Graph{

public:
  vector<vector<int>> graphs;
  vector<bool> check; // For DFS
  vector<ll> dist;   // For BFS
  queue<int> q; // For BFS

  Graph(int n){
    graphs.resize(n);
    init(n);
  }
  ~Graph(){}

  void addedge(int u, int v){
    u--; v--;
    graphs[u].push_back(v);
    //graphs[v].push_back(u);
  }

  void addedge_cin(int m){
    rep(i,m){
      int a, b;
      cin >> a >> b;
      addedge(a, b);
    }
  }

  void init(int n){
    check.resize(n, false);
    dist.resize(n, -1);
  }

  void reset(){
    rep(i,check.size()){
      check[i]=false;
      dist[i]=-1;
    }
  }

  void dfs(int v)
  {
    check[v] = true;

    for(auto next_v : graphs[v]){
      if(check[next_v]) continue;
      dfs(next_v);
    }
  }

  void bfs(int v)//----------------------
  {
    dist[v] = 0;
    q.push(v);

    while(!q.empty()){
      int cur_v = q.front();
      q.pop();

      for(int next_v : graphs[cur_v]){
        if(dist[next_v] != -1){
          continue;
        }

        dist[next_v] = dist[cur_v] + 1;
        q.push(next_v);
      }
    }
  }//-----------------------

};

int main(void) {
  int n;
  cin >> n;
  Graph g(n);

  rep(i,n){
    int ver, num;
    cin >> ver >> num;
    rep(j,num){
      int tmp;
      cin >> tmp;
      g.addedge(ver, tmp);
    }
  }

  g.bfs(0);

  rep(i,n){
    prt2(i+1, g.dist[i]);
  }

}