#include <iostream>
#include <fstream>
#include <vector>
#define pb push_back

using namespace std;

const int MAXN = 100010;
ifstream fin("dfs.in");
ofstream fout("dfs.out");

vector<int> edges[MAXN];
bool used[MAXN];
int n, m, nr;

void read() {
    fin >> n >> m;
    for (int i = 0; i < n; ++i) {
        int x, y;
        fin >> x >> y;
        edges[x].pb(y);
        edges[y].pb(x);
    }
}

void dfs(int node) {
    used[node] = 1;
    for (const auto& it: edges[node])
        if (!used[it])
            dfs(it);
}

void solve() {
    for (int i = 1; i <= n; ++i)
        if (!used[i]) {
            ++nr;
            dfs(i);
        }
}

int main() {
    read();
    solve();
    fout << nr;
    return 0;
}