#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define all(x) (x).begin(), (x).end()
bool be;
constexpr int N = 1e5 + 5;
int n, m, dep[N];
vector<int>e[N], vec;
bool vis[N];
void dfs(int u, int f)
{
	vis[u] = 1;
	vec.emplace_back(u);
	dep[u] = dep[f] + 1;
	for (int v : e[u]) {
		if (v != f) {
			dfs(v, u);
		}
	}
}
int getlen(int u)
{
	vec.clear();
	dfs(u, u);
	int d = 0, id = 0;
	for (int x : vec) {
		if (dep[x] > d) {
			d = dep[x];
			id = x;
		}
		dep[x] = 0;
	}
	dfs(id, id);
	int ans = 0;
	for (int x : vec) {
		ans = max(ans, dep[x]);
	}
	return ans;
}
bool en;
int main() {
	cerr << (&be - &en) / 1024.0 / 1024 << " MB\n--------------------------------" << endl;
#ifdef IAKIOI
	freopen("in.in", "r", stdin);
//	freopen("out.out", "w", stdout);
#endif
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cin >> n >> m;
	for (int i = 1; i <= m; ++i) {
		int u, v;
		cin >> u >> v;
		e[u].emplace_back(v);
		e[v].emplace_back(u);
	}
	int ans = 0;
	for (int i = 1; i <= n; ++i) {
		if (!vis[i]) {
			ans += getlen(i);
		}
	}
	cout << ans << endl;
	return 0;
}