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


ifstream f("dfs.in");
ofstream f2("dfs.out");

int viz[100001], n, m, s, x, y, plecare, i;

vector<int> listadeAdiacenta[100001];

int main()
{
    f >> n >> m;
    int insule = 0;

    for(i = 1; i <= n; i++){
        viz[i] = 0;
    }

    for(i = 1; i <= m; i++){
        f >> x >> y;
        listadeAdiacenta[x].push_back(y);
        listadeAdiacenta[y].push_back(x);
    }


    for(i = 1; i <= n; i++){
        if(viz[i] == 0){
            vector <int> lista = listadeAdiacenta[i];
            viz[i] = 1;
            for(vector <int> :: iterator it = lista.begin(); it != lista.end(); ++it){
                int currentValue = *it;
                viz[currentValue] = 1;
            }
        }
        else{
            continue;
        }
        insule++;
    }
    f2 << insule;
    return 0;
}