#include <bits/stdc++.h>
using namespace std;
#define lg long long
const lg N = 2e5+5;
vector<lg> adj[N], path;
lg dist[N], mxmnode, vis[N];
void dfs(lg src, lg par = -1, lg d = 1)
{
path.push_back(src);
vis[src] = true;
dist[src] = d;
if(dist[src] > dist[mxmnode])
{
mxmnode = src;
}
for(auto it : adj[src])
{
if(it == par) continue;
dfs(it, src, d+1);
}
return;
}
int main()
{
lg n, m;
cin >> n >> m;
for(int i = 0; i < m; i++)
{
lg u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
lg ans = 0;
for(int i = 1; i <= n; i++)
{
if(vis[i]) continue;
path.clear();
dfs(i, -1);
for(auto it : path) dist[it] = 0;
path.clear();
dfs(mxmnode, -1);
ans += dist[mxmnode];
mxmnode = 0;
}
cout << ans << '\n';
}
