package com.company;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        class Relationships {
            List<Integer> friends;

            public Relationships() {
                friends = new ArrayList<>();
            }
        }

        Scanner scan = new Scanner(System.in);

        //n
        int friendsCount = scan.nextInt();

        Relationships[] relationships = new Relationships[friendsCount];
        for(int i = 0; i < friendsCount; i++) relationships[i] = new Relationships();

        //m
        int pairsCount = scan.nextInt();
        for(int i = 0; i < pairsCount; i++) {
            int personA = scan.nextInt();
            int personB = scan.nextInt();

            relationships[personA].friends.add(personB);
            relationships[personB].friends.add(personA);
        }

        int invitedCount = friendsCount;
        boolean hasBeenDeleted = false;
        do {
            for (int i = 0; i < friendsCount; i++) {
                if (!(relationships[i].friends.size() >= 3) || !(invitedCount - relationships[i].friends.size() >= 3)) {
                    hasBeenDeleted = true;
                    for (int f : relationships[i].friends) {
                        relationships[f].friends.remove(i);
                    }
                    invitedCount--;
                    break;
                }
            }
        } while(hasBeenDeleted);

        System.out.println(invitedCount);
    }
}