// Super Idol的笑容
// 都没你的甜
// 八月正午的阳光
// 都没你耀眼
// 热爱105°C的你
// 滴滴清纯的蒸馏水
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << ": " << x << endl
#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define lb lower_bound
#define ub upper_bound
#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()
#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
//change less to less_equal for non distinct pbds, but erase will bug
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
int n,m;
vector<int> al[100005];
bool vis[100005];
ii dfs(int i,int p){
vis[i]=true;
ll mx=1;
vector<ll> child={0,0};
for (auto &it:al[i]){
if (it==p) continue;
auto temp=dfs(it,i);
mx=max(mx,temp.fi);
child.pub(temp.se);
}
sort(all(child));
reverse(all(child));
mx=max(mx,child[0]+child[1]+1);
return {mx,child[0]+1};
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin.exceptions(ios::badbit | ios::failbit);
cin>>n>>m;
int a,b;
rep(x,0,m){
cin>>a>>b;
al[a].pub(b);
al[b].pub(a);
}
int ans=0;
rep(x,1,n+1) if (!vis[x]) ans+=dfs(x,-1).fi;
cout<<ans<<endl;
}
