#include <bits/stdc++.h>

using namespace std;

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

const int NMAX = 100010;
vector<int> muchii[NMAX];
vector<int>::iterator it;
int n,m;
bitset<NMAX> mark;
queue<int> coada;

void citire()
{
    in>>n>>m;
    int x,y;
    for(int i=1;i<=m;i++)
    {
        in>>x>>y;
        muchii[x].push_back(y);
        muchii[y].push_back(x);
    }
    in.close();
}

void bf(int x)
{
    coada.push(x);
    mark.set(x);
    while(!coada.empty())
    {
        int y = coada.front();
        for(it = muchii[y].begin();it<muchii[y].end();it++)
            if(!mark.test(*it))
        {
            coada.push(*it);
            mark.set(*it);
        }
    coada.pop();
    }
}

int main()
{
    citire();
    int nr = 0;
    for(int i=1;i<=n;i++)
        if(!mark.test(i))
    {
        bf(i);
        nr++;
    }
    out<<nr<<"\n";
    out.close();
    return 0;
}