#include <iostream>
#include <fstream>
#include <vector>
#define MAXN 100001
using namespace std;

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

vector <int> v[MAXN];
int viz[MAXN], n, m, nr;

void read()
{
    int x, y;

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

void write()
{
    fout << nr;
}

void movement(int vf)
{
    vector <int>::iterator it;

    for (it = v[vf].begin(); it != v[vf].end(); ++it)
        if (viz[*it] == 0) {
            viz[*it] = 1;
            movement(*it);
        }
}

void solve()
{
    for (int i = 1; i <= n; ++i)
        if (viz[i] == 0) {
            viz[i] = 1;
            movement(i);
            nr++;
        }
}

int main()
{
    read();
    solve();
    write();
    return 0;
}