#include <bits/stdc++.h>
using namespace std;


template <typename A, typename B>
string to_string(pair<A, B> p);
 
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);
 
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);
 
string to_string(const string& s) {
  return '"' + s + '"';
}
 
string to_string(const char* s) {
  return to_string((string) s);
}
 
string to_string(bool b) {
  return (b ? "true" : "false");
}
 
string to_string(vector<bool> v) {
  bool first = true;
  string res = "{";
  for (int i = 0; i < static_cast<int>(v.size()); i++) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(v[i]);
  }
  res += "}";
  return res;
}
 
template <size_t N>
string to_string(bitset<N> v) {
  string res = "";
  for (size_t i = 0; i < N; i++) {
    res += static_cast<char>('0' + v[i]);
  }
  return res;
}
 
template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}
 
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
 
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}
 
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}
 
void debug_out() { cerr << endl; }
 
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}
 
#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
#define endl '\n'
#define __ ios_base::sync_with_stdio(0);cin.tie(0);
#define fi first
#define se second
#define pb push_back
#define all(x) x.begin(),x.end()
#define forn(i,a,n) for(int i=a; i < n; i++)
typedef long long int lli;
typedef long double Double;
typedef pair<int,int> pii;
typedef pair<lli,lli> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
const int mod = 1e9+7;
const int inf= 1<<30;
const int maxn = 200005;


struct union_find
{
	vector<int> p,sz;
	union_find(int n) : p(n, -1),sz(n,1){}

	bool join(int u, int v){
		if ((u = root(u)) == (v = root(v)))
			return false;
		if (p[u] > p[v])
			swap(u, v);
		p[u] += p[v];
		p[v] = u;
		sz[u]+=sz[v];
		return true;
	}

	int root(int u){
		return p[u] < 0 ? u : p[u] = root(p[u]);
	}

	bool connected(int u,int v){
		return root(u) == root(v);
	}

	int getsz(int u){
		return sz[root(u)];
	}
};

int main(){__
	int n,m;
	cin >> n >> m;
	union_find uf(n+1);
	for(int i=1; i <=m; i++){
		int u,v;
		cin >> u >> v;
		uf.join(u,v);
	}

	vi tam;
	set<int> raices;
	for(int i=1; i <=n; i++){
		int r = uf.root(i);
		if(raices.find(r) != raices.end()) continue;
		raices.insert(r);
		int t = uf.getsz(i);
		tam.pb(t);
	}

	sort(all(tam));
	reverse(all(tam));
	debug(tam);
	int quitados = 0;
	int ans =0;
	while(!tam.empty()){
		int mini = tam.back();
		ans+= (mini - quitados);
		int quitar = mini;
		while(!tam.empty() && tam.back() == mini){
			tam.pop_back();
		}
		quitados = mini;
	}
	cout << ans << endl;
	return 0;
}


Measured memory_bytes: 14996