#include <bits/stdc++.h>


using namespace std;

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

class Graph {

private:

    int nodes, edges, starting_node,dfs_time;

    int *color;  //3 color 0 -> white, 1 -> gray, 2 -> black
    int *distances;
    int *visited;
    pair<int,int>* times;
    vector<int> *preds; //not using yet
    vector<int> *adjacency_list;


    bool oriented;

public:
    Graph(int nodes = 0, int edges = 0, int starting_node = 0, bool oriented = true) :
            nodes(nodes), edges(edges), oriented(oriented), starting_node(starting_node) {

        dfs_time = 0;

        color = (int *) calloc(nodes + 1, sizeof(int));
        distances = (int *) calloc(nodes + 1, sizeof(int));
        times = (pair<int,int>*)calloc(nodes + 1, sizeof (pair<int,int>));
        preds = new vector<int>[nodes + 1];
        adjacency_list = new vector<int>[nodes + 1];
        visited = (int *) calloc(nodes + 1, sizeof(int));

    }

    ~Graph() {

        free(color);
        free(distances);
        free(visited);
        free(times);
        delete[] preds;
        delete[] adjacency_list;

    }

    void get_times(){
        for(int i = 1;i<nodes+1;i++){
            cout << times[i].first << ' ' << times[i].second;
            cout<<'\n';
        }
    }
    int getNodes() const {
        return nodes;
    }

    void setNodes(int nodes) {
        nodes = nodes;
    }

    int getEdges() const {
        return edges;
    }

    void setEdges(int edges) {
        edges = edges;
    }

    bool isOriented() const {
        return oriented;
    }

    void setOriented(bool oriented) {
        Graph::oriented = oriented;
    }

    void set_graph() {
        int x, y;
        if (isOriented()) {
            for (int i = 1; i <= edges; i++) {
                fin >> x >> y;
                adjacency_list[x].push_back(y);
            }
        } else {
            for (int i = 1; i <= edges; i++) {
                fin>>x>>y;
                adjacency_list[x].push_back(y);
                adjacency_list[y].push_back(x);
            }
        }
    }

    void show_graph() {
        for (int i = 1; i <= nodes; i++) {
            cout << i << ":";
            for (int neighbor : adjacency_list[i]) {
                cout << neighbor << ' ';
            }
            cout << '\n';
        }
    }

    void show_distances() {
        BFS();
        for (int i = 1; i < nodes + 1; i++) {
            fout << distances[i] - 1 << ' ';
        }
    }

    void conex_components(){
        int cnt = 0;
        for(int i = 1;i<nodes+1;i++){
            if(!visited[i]) {
                DFS(i);
                cnt++;
            }
        }
        fout<<cnt;
    }

private:

    void BFS() {

        queue<int> que;
        que.push(starting_node);

        visited[starting_node] = 1;
        color[starting_node] = 1;
        distances[starting_node] = 1;

        while (!que.empty()) {

            int node = que.front();
            que.pop();

            for (int neighbor : adjacency_list[node]) {

                if (color[neighbor] == 0) {
                    que.push(neighbor);
                    color[neighbor] = 1;
                    visited[neighbor] = 1;
                    distances[neighbor] = distances[node] + 1;
                }

            }

            color[node] = 2;
        }

    }

    void DFS(int start = 1) {

        dfs_time += 1;
        times[start].first = dfs_time;
        color[start] = 1;
        visited[start] = 1;

        for(int neighbor : adjacency_list[start]){
            if(!visited[neighbor]){
                DFS(neighbor);
            }
        }

        color[start] = 2;
        dfs_time+=1;
        times[start].second = dfs_time;
    }

};


int main() {

    int n, m;

    fin >> n >> m;
    Graph g(n, m, 0, false);
    g.set_graph();
    g.conex_components();
    return 0;
}