#include <bits/stdc++.h>

using namespace std;

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

const int nmax = 10000001;
int n, m;
int viz[nmax];
vector <int> h[nmax];

void Citire()
{
    int x, y;
    fin >> n >> m;
    for (int i = 1; i <= m; i++)
    {
        fin >> x >> y;
        h[x].push_back(y);
        h[y].push_back(x);
    }
    for (int i = 1; i <= n; i++)
        sort(h[i].begin(), h[i].end());
}

void DFS(int k)
{
    viz[k] = 1;
    for (auto i : h[k])
        if (viz[i] == 0) DFS(i);
}

int main()
{
    int cnt = 0;
    Citire();
    for (int i = 1; i <= n; i++)
        if(!viz[i])
        {
            cnt++;
            DFS(i);
        }
    fout << cnt;

    return 0;
}