#include"bits/stdc++.h" #define ll long long using namespace std; vector<ll>g[100005]; bool v[100005]; ll d; ll u; void dfs(ll n, ll p, ll l){ v[n]=true; if(l>d){ d=l; u=n; } for(ll x:g[n]){ if(x!=p) dfs(x,n,l+1); } } ll ok(ll s){ d=-1; dfs(s,-1,1); ll st=u; d=-1; dfs(st,-1,1); return d; } int main() { ll n; ll m; cin>>n>>m; for(ll i=0;i<m;i++) { ll x,y; cin>>x>>y; g[x].push_back(y); g[y].push_back(x); } ll t=0; for(ll i=1;i<=n;i++) { if(!v[i]) { t+=ok(i); } } cout<<t<<endl; return 0; }