sol

#include <bits/stdc++.h>

using namespace std;
vector<int> a[10001];
bool vis[10001];
int n, m, u, v;
void dfs(int u) {
    vis[u] = true;
    for (int i = 0; i < a[u].size(); ++i) {
        int v = a[u][i];
        if (!vis[v])
            dfs(v);
    }
}
int main() {
    cin >> n >> m;
    for (int i = 1; i <= m; ++i) {
        cin >> u >> v;
        a[u].push_back(v);
        a[v].push_back(u);
    }
    int ans = 0;
    for (int i = 1; i <= n; ++i) {
        if (vis[i] == false) {
            ans++;
            dfs(i);
        }
    }
    cout << ans << endl;

    return 0;
}

#include <bits/stdc++.h>

using namespace std;
vector<int> a[10001];
bool vis[10001];
int n, m, u, v, en;
int h[10001];  // h[i] 表示 i 出发的第一条边的编号
struct Edge {
    int u, v, nxt;
} e[400000];
void add(int u, int v) {
    en++;  //  edge number
    e[en].u = u;
    e[en].v = v;
    e[en].nxt = h[u];
    h[u] = en;
}
void dfs(int u) {
    vis[u] = true;
    for (int i = h[u]; i > 0; i = e[i].nxt) {
        int v = e[i].v;
        if (!vis[v])
            dfs(v);
    }
}
int main() {
    cin >> n >> m;
    for (int i = 1; i <= m; ++i) {
        cin >> u >> v;
        add(u, v);
        add(v, u);
    }
    int ans = 0;
    for (int i = 1; i <= n; ++i) {
        if (vis[i] == false) {
            ans++;
            dfs(i);
        }
    }
    cout << ans << endl;

    return 0;
}