#include<bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#define endl '\n'
#define fr first
#define sc second
#define mp make_pair
#define pb push_back
#define bn binary_search
#define lb lower_bound
#define up upper_bound
#define np next_permutation
#define all(x) x.begin(), x.end()
#define sz(x) (int) x.size()
#define mdc(x, y) __gcd(x, y)
#define dbg(x) cout << #x << ": " << "[ " << x << " ]\n"
typedef int ii;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int MAX = 2e6 + 15;
const int MOD = 1e9 + 7;
const int INF = 0x3f3f3f3f;
const ll LLINF = 0x3f3f3f3f3f3f3f3f;
const int VAR[4] = {-1, 1, 0, 0};
ll n, m, v1, v2, ans, mx, id;
vector<int> adj[MAX], seen(MAX, false);
void setIO(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
}
void dfs(int x, int p, int d){
seen[x] = true;
if(d > mx) id = x, mx = d;
for(auto v : adj[x]){
if(v == p) continue;
dfs(v, x, d + 1);
}
}
int diam(int r){
mx = -INF;
dfs(r, -1, 1);
mx = -INF;
dfs(id, -1, 1);
return mx;
}
int main(){
setIO();
cin >> n >> m;
while(m--){
int u, v;
cin >> u >> v;
adj[u].pb(v);
adj[v].pb(u);
}
for(int i = 1; i <= n; i++){
if(!seen[i]) ans += diam(i);
}
cout << ans << '\n';
return 0;
}
