#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
const int MAXN = 100005;
vector<int> adj[MAXN];
bool visited[MAXN];
vector<int> nodes;
void find_nodes(int u) {
visited[u] = true;
nodes.push_back(u);
for (int v : adj[u]) {
if (!visited[v]) find_nodes(v);
}
}
pair<int, int> bfs(int start_node) {
queue<pair<int, int>> q;
q.push({start_node, 1});
static int dist[MAXN];
for (int node : nodes) dist[node] = -1;
dist[start_node] = 1;
pair<int, int> farthest = {start_node, 1};
while (!q.empty()) {
int u = q.front().first;
int d = q.front().second;
q.pop();
if (d > farthest.second) farthest = {u, d};
for (int v : adj[u]) {
if (dist[v] == -1) {
dist[v] = d + 1;
q.push({v, d + 1});
}
}
}
return farthest;
}
int main() {
int n, m;
cin >> n >> m;
for (int i = 0; i < m; i++) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
long long total_diameter = 0;
for (int i = 1; i <= n; i++) {
if (!visited[i]) {
nodes.clear();
find_nodes(i);
pair<int, int> p1 = bfs(nodes[0]);
pair<int, int> p2 = bfs(p1.first);
total_diameter += p2.second;
}
}
cout << total_diameter << endl;
return 0;
}
