drzewka

#include <iostream>

using namespace std;

int main ()
{
    int m,n;

    cin >> n >> m;

    n = m;

    int tab[m][3];

    for (int i=0; i<m; i++)
    {
        cin >> tab[i][0] >> tab[i][1];
        tab[i][2] = 0;
    }

    for (int i=0; i<m; i++)
    {
        for (int j=0; j<m; j++)
        {
            if (tab[j][0] == tab[i][1] or tab[j][1] == tab[i][1])
            {
                if (tab[j][1] == tab[i][1]) // prawy -> lewy
                {
                    for (int k=0; k<m; k++)
                    {
                        if ((tab[j][0] == tab[k][0] or tab[j][0] == tab[k][1]) and (tab[k][0] == tab[i][0] or tab[k][1] == tab[i][0])) // j 0 -> sasiad
                        {
                            if(tab[i][2] == 0)
                            {
                                n--;
                            }
                            if(tab[j][2] == 0)
                            {
                                n--;
                            }
                            if(tab[k][2] == 0)
                            {
                                n--;
                            }
                            tab[k][2] = 1;
                            tab[j][2] = 1;
                            tab[i][2] = 1;
                        }
                    }
                }
                else if (tab[j][0] == tab[i][1])
                {
                    for (int k=0; k<m; k++)
                    {
                        if ((tab[j][1] == tab[k][0] or tab[j][1] == tab[k][1]) and (tab[k][0] == tab[i][0] or tab[k][1] == tab[i][0])) // j 0 -> sasiad
                        {
                            tab[k][2] = 1;
                            tab[j][2] = 1;
                            tab[i][2] = 1;
                        }
                    }
                }
            }
        }
    }
    /*
    int wynik=0;
    for (int i=0; i<m; i++)
    {
        if (tab[i][2] == 0)
        {
            wynik++;
        }
    }
    */
    cout << n;
}