#include <bits/stdc++.h>
using namespace std;
const int nx=1e5+5;
int n, m, u, v, vs[nx], res;
pair<int, int> dp[nx];
vector<int> d[nx];
void dfs(int u, int p)
{
vs[u]=1;
dp[u]={1, u};
for (auto v:d[u]) if (v!=p) dfs(v, u), dp[u]=max(dp[u], {dp[v].first+1, dp[v].second});
}
int main()
{
cin.tie(NULL)->sync_with_stdio(false);
cin>>n>>m;
for (int i=1; i<=m; i++) cin>>u>>v, d[u].push_back(v), d[v].push_back(u);
for (int i=1; i<=n; i++)
{
if (vs[i]) continue;
dfs(i, i);
int st=dp[i].second;
dfs(st, st);
res+=dp[st].first;
}
cout<<res;
}
