#define MAX_N 100000

#include <fstream>
#include <vector>
#include <bitset>
using namespace std;

ifstream fin("biconex.in");
ofstream fout("biconex.out");

int n, m, cb;
vector<int> G[MAX_N + 1];
bitset<MAX_N + 1> invalid;
bitset<MAX_N + 1> vizitat;

void Invalideaza(int nod);
void Df(int nod, int& nr);

int main()
{
    fin >> n >> m;

    for (int i = 1, x, y; i <= m; ++i)
    {
        fin >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }

    for (int i = 1; i <= n; ++i)
    {
        if (G[i].size() <= 1)
        {
            Invalideaza(i);
        }
    }

    for (int i = 1, aux = 0; i <= n; ++i)
    {
        if (!invalid[i] && !vizitat[i])
        {
            Df(i, aux);
        }
    }

    fout << cb;

    fin.close();
    fout.close();
    return 0;
}

void Invalideaza(int nod)
{
    ++cb;
    invalid[nod] = true;

    if (G[G[nod].front()].size() <= 2)
    {
        Invalideaza(G[nod].front());
    }
}

void Df(int nod, int& nr)
{
    vizitat[nod] = true;

    for (int vecin : G[nod])
    {
        if (invalid[vecin]) { continue; }
        if (vizitat[vecin]) { ++nr; continue; }

        --nr;
        Df(vecin, nr);
    }

    if (nr == 1)
    {
        ++cb;
    }
}