#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl '\n'
const int N = 1e5+5;
vector<int> adj[N];
int dep[N];
int dep2[N];
int vis[N];
int bfs(int src){
vis[src] = 1;
queue<int> q;
q.push(src);
pair<int,int> mxDep {0,src};
while(q.size()){
int node = q.front(); q.pop();
for(auto ch : adj[node]){
if(vis[ch]) continue;
q.push(ch);
vis[ch] = 1;
dep[ch] = dep[node] + 1;
mxDep = max(mxDep,{dep[ch],ch});
}
}
q.push(mxDep.second);
vis[mxDep.second] = 2;
int ret = 1;
while(q.size()){
int node = q.front(); q.pop();
for(auto ch : adj[node]){
if(vis[ch] == 2) continue;
q.push(ch);
vis[ch] = 2;
dep2[ch] = dep2[node] + 1;
ret = max(ret , dep2[ch] + 1);
}
}
return ret;
}
void solve(){
int n,m;
cin>>n>>m;
for(int i=0;i<m;i++){
int a,b;
cin>>a>>b;
adj[a].push_back(b);
adj[b].push_back(a);
}
int ans = 0;
for(int i=1;i<=n;i++){
if(vis[i]) continue;
ans += bfs(i);
}
cout<<ans<<endl;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int t=1;
//cin>>t;
while(t--){
solve();
}
return 0;
}
