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 <iostream>
#include <queue>
#define MAX 100
using namespace std;

static const int INFTY = (1 << 21);
int n, M[MAX][MAX];
int d[MAX];

void bfs(int s) {
	queue<int> q;
	q.push(s);
	for (int i = 0; i < n; i++) {
		d[i] = INFTY;
	}
	d[s] = 0;
	int u;
	while (!q.empty())
	{
		u = q.front();
		q.pop();
		for (int v = 0; v < n; v++) {
			if (M[u][v] == 0)
				continue;
			if (d[v] != INFTY)
				continue;
			d[v] = d[u] + 1;
			q.push(v);
		}
	}
	for (int i = 0; i < n; i++) {
		cout << i + 1 << " " << ((d[i] == INFTY) ? (-1) : d[i]) << endl;
	}
}

int main()
{
	cin >> n;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			M[i][j] = 0;
		}
	}
	for (int i = 0; i < n; i++) {
		int u, k, v;
		cin >> u >> k;
		u--;
		for (int j = 0; j < k; j++) {
			cin >> v;
			v--;
			M[u][v] = 1;
		}
	}
	bfs(0);

	return 0;
}

C++: #include <iostream>
#include <queue>

using namespace std;
#define N 100

int n ,M[N][N];
int d[N];

void bfs(int s) {
    queue<int> q;
    q.push(s);
    for(int i=0; i<n; i++) {
        d[i] = -1;
    }
    d[s] = 0;
    int u;
    while(!q.empty()) {
        u = q.front();
        q.pop();
        for(int v=0; v<n; v++) {
            if(M[u][v]==0) {
                continue;
            }
            if(d[v]!=-1) {
                continue;
            }
            d[v] = d[u] + 1;
            q.push(v);
        }
    }
    for(int i=0; i<n; i++) {
        cout << i+1 << " " << d[i] << endl;
    }
}

int main() {
    int u, k, v;

    cin >> n;
    for(int i=0; i<n; i++) {
        for(int j=0; j<n; j++) {
            M[i][j] = 0;
        }
    }

    for(int i=0; i<n; i++) {
        cin >> u >> k;
        u--;
        for(int j=0; j<k; j++) {
            cin >> v;
            v--;
            M[u][v] = 1;
        }
    }

    bfs(0);

    return 0;
}

C++: #include<iostream>
#include<vector>
#include<queue>
#include<algorithm>

using namespace std;

int main() {
	int n, u, k, v;
	cin >> n;
	vector<int> ans(n,100000000000);
	vector<vector<int>> adj(n);
	for (int i = 0; i < n; i++) {
		cin >> u >> k;
		while (k--)cin >> v, adj[u-1].push_back(v-1);
	}
	queue<pair<int, int>> q;//<idx,path>
	q.push(pair<int, int>(0, 1));
	while (!q.empty()) {
		auto tmp = q.front(); q.pop();
		ans[tmp.first] = min(ans[tmp.first], tmp.second);
		for (int i = 0; i < adj[tmp.first].size(); i++) q.push(pair<int, int>(adj[tmp.first][i], tmp.second+1));
	}
	for (int i = 0; i < n; i++)	cout << i + 1 << " " << ans[i]-1 << endl;
	
}

C++: #define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
using namespace std;
static const int N = 100;

int n;
int M[N][N];
int vis[N];
int seq[N];

void bfs_print() {
	for (int i = 0; i < n; i++) {
		cout << i + 1 << ' ' << seq[i]<<endl;
	}
}

int main() {
	cin >> n;
	int u, k;
	int index;

	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			M[i][j] = 0;
		}
	}

	for (int i = 0; i < n; i++) {
		cin >> u >> k;
		for (int j = 0; j < k; j++) {
			cin >> index;
			M[u - 1][index - 1] = 1;
		}
	}
	for (int i = 0; i < n; i++) {
		seq[i] = 0;
		vis[i] = 0;
		if(i >0) seq[i] = -1;
	}

	queue<int> q;
	q.push(0);
	seq[0] = 0;
	int t;
	while (not q.empty()) {
		vis[q.front()] = 1;
		for (int i = 0; i < n; i++) {
			if (M[q.front()][i] == 1 and vis[i] == 0) {
				vis[i] = 1;
				seq[i] = seq[q.front()] + 1;
				q.push(i);
			}
		}
		q.pop();
	}

	bfs_print();
}
//
//void dfs_visit(int u) {
//	color[u] = GRAY;
//	d[u] = ++tt;
//	for (int v = 0; v < n; v++) {
//		if (M[u][v] == 1 && color[v] == WHITE) {
//			dfs_visit(v);
//		}
//	}
//	color[u] = BLACK;
//	f[u] = ++tt;
//}
//
//void dfs_print() {
//	for (int i = 0; i < n; i++) color[i] = WHITE;
//	tt = 0;
//	for (int i = 0; i < n; i++) {
//		if (color[i] == WHITE) {
//			dfs_visit(i);
//		}
//	}
//
//	for (int i = 0; i < n; i++) {
//		cout << i + 1 << ' ' << d[i] << ' ' << f[i] << endl;
//	}
//}
//

C++: #include <algorithm>
#include <iostream>
#include <list>
#include <vector>

class TNode
{
	int FIndex;
	std::list<TNode*> FTarget;
public:
	TNode(int Index)
	: FIndex(Index)
	{
	}
	
	void Push(TNode* New)
	{
		FTarget.push_back(New);
	}
	
	int Distance(const TNode* Target)const
	{
		if(Target == this) return 0;
		if(std::find(FTarget.begin(), FTarget.end(), Target) != FTarget.end()) return 1;
		int Minimum = -2;
		for(std::list<TNode*>::const_iterator It = FTarget.begin(); It != FTarget.end(); ++It){
			int Distance = (*It)->Distance(Target);
			if(Distance >= 0 && (Minimum > Distance || Minimum < 0)){
				Minimum = Distance;
			}
		}
		return 1 + Minimum;
	}
};

class TGraph
{
	std::vector<TNode*> FNodes;
public:
	TGraph(int Count)
	: FNodes(Count)
	{
		for(int i = 0; i < Count; ++i){
			FNodes[i] = new TNode(i + 1);
		}
	}
	
	~TGraph()
	{
		for(unsigned int i = 0; i < FNodes.size(); ++i){
			delete FNodes[i];
		}
	}
	
	void InputNode()
	{
		int Index;
		std::cin >> Index;
		int BranchCount;
		std::cin >> BranchCount;
		for(int i = 0; i < BranchCount; ++i){
			int Target;
			std::cin >> Target;
			FNodes[Index - 1]->Push(FNodes[Target - 1]);
		}
	}
	
	int MeasureDistance(int Start, int End)const
	{
		return FNodes[Start - 1]->Distance(FNodes[End - 1]);
	}
};

int main()
{
	int Count;
	std::cin >> Count;
	TGraph Graph(Count);
	for(int i = 0; i < Count; ++i){
		Graph.InputNode();
	}

	for(int i = 0; i < Count; ++i){
		std::cout << i + 1 << " " << Graph.MeasureDistance(1, i + 1) << std::endl;
	}
	return 0;
}

C++: #include <iostream>
#include <queue>
#include <vector>
#define pb push_back
using namespace std;
queue<int> q;
vector<int> v[110];
bool seen[110] = {0};
int main() {
    int n; cin >> n;
    for (int i = 0; i < n; i++) {
        int u, k; cin >> u >> k;
        while (k--) {
            int tmp; cin >> tmp;
            v[u].pb(tmp);
        }
    }
    q.push(1);
    int d[n + 1];
	for (int i = 0; i <= n; i++)
		d[i] = -1;
    d[1] = 0; seen[1] = 1;
    while (!q.empty()) {
        for (int x: v[q.front()]) {
            if (!seen[x]) {
                q.push(x);
                seen[x] = 1;
                d[x] = d[q.front()] + 1;
            }
        }
        q.pop();
    }
    for (int i = 1; i <= n; i++)
        cout << i << ' ' << d[i] << '\n';
    return 0;
}