#include <iostream>
#include <vector>
#include <queue>
#include <fstream>

using namespace std;

vector<int> v[100000];
int culoare[100000], parinte[100000], inceput[100000], sfarsit[100000];
queue<int> q;

int n, m, i, j, x, y, nod, sursa, contor_timp, k = 0;

void DFS(int nod)
    {
        contor_timp ++;
        inceput[nod] = contor_timp;
        culoare[nod] = 1;

        for (i = 0; i < v[nod].size(); i++)
            if(culoare[v[nod][i]] == 0)
                {
                    parinte[v[nod][i]] = nod;
                    DFS(v[nod][i]);
                }
        contor_timp ++;
        sfarsit[nod] = contor_timp;
        culoare[nod] = 2;
    }

int main()
{
    ifstream f("dfs.in");
    ofstream g("dfs.out");

    f >> n;
    f >> m;

    for(i = 1; i <= 100; i++)
        {
         culoare[i] = 0;
         parinte[i] = 0;
         inceput[i] = 0;
         sfarsit[i] = 0;
        }
    contor_timp = 0;

    for (i = 0; i < m; i++)
        {
            f >> x >> y;
            v[x].push_back(y);
            v[y].push_back(x);
        }

    sursa = 1;

    for(i = 0; i < v[sursa].size(); i++)
        if(culoare[v[sursa][i]] == 0)
            DFS(sursa);

    for(i = 1; i <= n; i++)
        if (culoare[i] == 0)
            {
                DFS(i);
                k++;
            }

    g << k;

    return 0;
}