#include <fstream>
#include <list>
#include <vector>
#include <stack>


void dfs(int node_nr,
         const std::vector< std::list<int> > &graph,
         std::vector<bool> &visited)
{
    visited[node_nr] = true;
    for (auto &i : graph[node_nr])
        if (!visited[i])
            dfs(i, graph, visited);
}

void dfs_iter(int node_nr,
         const std::vector< std::list<int> > &graph,
         std::vector<bool> &visited)
{
    std::stack<int> nodes;
    nodes.push(node_nr);

    while (!nodes.empty()) {
        int node = nodes.top();
        nodes.pop();

        if (!visited[node]) {
            visited[node] = true;
            for (auto &i : graph[node])
                nodes.push(i);
        }
    }
}


int main()
{
    std::ifstream in("dfs.in");
    std::ofstream out("dfs.out");

    int N, M;
    in >> N >> M;

    std::vector< std::list<int> > graph(N+1);

    for (int i = 0; i < M; ++i) {
        int x, y;
        in >> x >> y;

        graph[x].push_front(y);
        graph[y].push_front(x);
    }

    std::vector<bool> visited_nodes(N+1, false);
    int count = 0;
    for (int i = 1; i <= N; ++i)
        if (!visited_nodes[i]) {
            ++count;
            dfs_iter(i, graph, visited_nodes);
        }

    out << count;

    in.close();
    out.close();

    return 0;
}