#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
#define ve vector<int>
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define pi pair<int,int>
#define all(v) v.begin(),v.end()
#define si(v) (int)v.size()
#define en '\n'
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define ordered_muiltiset tree<int, null_type,less_equal<>, rb_tree_tag,tree_order_statistics_node_update>
//#define int long long
using namespace std;
//using namespace __gnu_pbds;
typedef long long ll;
typedef unsigned long long ull;
const int N = 1e5 + 228;
const int big = 1e9;
//ordered_set os; // os.order_of_key(4), (*os.find_by_order(5))
int n, m, ans, k, gv, mxg;
bool mrk[N];
ve g[N];
void dfs(int v, int pr, int gl, bool mark){
if (mark) mrk[v] = 1;
if (gl > mxg){
mxg = gl;
gv = v;
}
for (int i = 0; i < si(g[v]); i++){
int u = g[v][i];
if (pr == u) continue;
dfs(u, v, gl + 1, mark);
}
}
//#undef int
int main(){
//#define int long long
iostream::sync_with_stdio(false); cin.tie(0); ios_base::sync_with_stdio(false); cout.tie(0);
//freopen("input.txt","r",stdin);
//freopen("output.txt","w",stdout);
cin >> n >> m;
for (int i = 1; i <= m; i++){
int a, b;
cin >> a >> b;
g[a].pb(b);
g[b].pb(a);
}
for (int i = 1; i <= n; i++){
if (!mrk[i]){
mxg = -1;
gv = 0;
dfs(i, -1, 0, 1);
int root = gv;
mxg = -1;
gv = 0;
dfs(root, -1, 0, 0);
ans += mxg + 1;
}
}
cout << ans;
return 0;
}
/*
*/
