#include <cstdio>
#include <stdio.h>
#include <stdbool.h>
#include <iostream>
#include <map>
#include <vector>
#include <climits>
#include <stack>
#include <string>
#include <queue>
#include <algorithm>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cmath>
#include <cctype>
#include <bitset>
#include <iomanip>
#include <cstring>
#include <numeric>
#include <cassert>
#include <random>
#include <chrono>
#include <fstream>
using namespace std;
#define int long long
#define pii pair<int, int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
vector<bool> visited;
vector<vector<int> > graph;
pii dfs(int node, int par){
pii res=mp(0, node);
visited[node]=1;
for (auto num:graph[node])if (num!=par)res=max(res, dfs(num, node));
return mp(res.fi+1, res.se);
}
int32_t main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, m, a, b, ans=0;
cin>>n>>m;
visited.resize(n+1);
graph.resize(n+1);
while (m--){
cin>>a>>b;
graph[a].pb(b);
graph[b].pb(a);
}
for (int i=1; i<=n; ++i)if (!visited[i])ans+=dfs(dfs(i, -1).se, -1).fi;
cout<<ans;
}
