#include <bits/stdc++.h>
using namespace std;

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

void DFS (vector<vector<int>> &graph, int node, unordered_set<int> &seen) {
    seen.insert(node);
    for (auto neighbour : graph[node]) {
        if (seen.find(neighbour) == seen.end())
            seen.insert(neighbour), DFS(graph, neighbour, seen);
    }
}

void count (vector<vector<int>> &graph) {
    unordered_set<int> comp;
    int ans = 0, n = graph.size() - 1;
    for (int i = 1; i <= n; ++i) {
        if (comp.find(i) == comp.end()) {
            ++ans;
            DFS(graph, i, comp);
        }
    }
    fout << ans;
}

int main()
{
    vector<vector<int>> nodes;
    int n, m;
    fin >> n >> m;
    nodes.resize(n + 1);
    while (m) {
        int x, y;
        fin >> x >> y;
        nodes[x].push_back(y);
        nodes[y].push_back(x);
        --m;
    }
    count(nodes);
    return 0;
}