import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.Stack;

class GraphDFS {
	int nodes;
	public Map<Integer, List<Integer>> adiacenta;

	public GraphDFS() {
		adiacenta = new HashMap<>();
	}

	public GraphDFS(int nodes, Map<Integer, List<Integer>> edges) {
		this.nodes = nodes;
		this.adiacenta = edges;
	}

	public void readData(String filename) throws IOException {
		Scanner input = new Scanner(new FileReader(filename));
		nodes = input.nextInt();
		int M = input.nextInt();

		for (int i = 1; i <= nodes; i++)
			adiacenta.put(i, new ArrayList<Integer>());

		int node1, node2;
		for (int i = 0; i < M; i++) {
			node1 = input.nextInt();
			node2 = input.nextInt();
			adiacenta.get(node1).add(node2);
			adiacenta.get(node2).add(node1);
		}
		input.close();
	}

}

public class Main {

	static int[] c;
	static int conex;

	public static void dfs(GraphDFS g) {
		int V = g.nodes;
		c = new int[V + 1]; // 0 - alb, 1 - gri, 2 - negru

		for (int u = 1; u <= V; u++) {
			c[u] = 0;
		}

		for (int u = 1; u <= V; u++) {
			if (c[u] == 0) {
				explorare(u, g);
				conex++;
			}
		}
	}

	public static void explorare(int u, GraphDFS g) {

		Stack<Integer> s = new Stack<>();
		c[u] = 1;
		s.push(u);

		for (int v = 0; v < g.adiacenta.get(new Integer(u)).size(); v++) {
			int n = g.adiacenta.get(new Integer(u)).get(v);

			if (c[n] == 0) {
				c[n] = 2;
				s.push(n);
			}
		}
		c[u] = 2;
	}

	public static void main(String[] args) throws IOException {
		GraphDFS g = new GraphDFS();
		g.readData("dfs.in");
		dfs(g);

		BufferedWriter write = new BufferedWriter(new FileWriter(new File("dfs.out")));
		write.write(conex + "");
		write.close();
	}
}