#include<bits/stdc++.h>
#define fi first
#define se second
#define pitem item*
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vl;
const int N=1e6+10;
const int SS=1<<19;
const int INFi=2e9;
const ll INFl=1e13;
const ll mod2=998244353;
const ll mod=1e9+7;
const ll mod3=1000696969;
const ll p=70032301;
const ull p2=913;
const int L=20;
int t[N],maxi,g;
bitset<N>vis;
vi graf[N];
void dfs(int v,int o,int gl){
vis[v]=1;
if(gl>maxi) maxi=gl,g=v;
for(auto u:graf[v]){
if(u==o) continue;
dfs(u,v,gl+1);
}
}
void solve(){
int n,m;
cin>>n>>m;
for(int a,b,i=1;i<=m;i++){
cin>>a>>b;
graf[a].push_back(b),graf[b].push_back(a);
}
int res=0;
for(int i=1;i<=n;i++){
if(vis[i]) continue;
dfs(i,i,0);
maxi=0;
dfs(g,g,0);
res+=maxi+1;
maxi=0;
}
cout<<res<<"\n";
}
int main(){
ios_base::sync_with_stdio(0),cin.tie(0);
int tt=1;
while(tt--) solve();
}
