#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
using ll = int_fast64_t;
using ull = uint_fast64_t;

using mint = modint998244353;

constexpr ll INF = 1ll << 60;

#define iscontain(container, value) (find(container.begin(), container.end(), value) != container.end())

template<typename T, typename D> void printelem(const T& container, const D& divide){
	for(const auto& i : container) cout << i << divide;
	cout << endl;
}
template<typename T> void printelem(const T& container) { printelem(container, ", "); }
template<typename T> T input() { T ret; cin >> ret; return ret; }

ll N, M;
vector<set<ll>> mate;

vector<ll> group;
vector<set<ll>> member;
vector<ll> belong;
void make_group(ll p, ll g){
	for(auto&& i : mate[p]){
		if(belong[i] != -1) continue;
		belong[i] = g;
		member[g].insert(i);
		group[g]++;
		make_group(i, g);
	}
}

int main(){
	//インプット
	cin >> N >> M;
	mate.resize(N*2);
	for(ll i = 0; i < M; i++){
		ll A, B;
		cin >> A >> B, A--, B--;
		mate[A].insert(B);
		mate[B].insert(A);
	}

	belong.resize(N*2, -1);
	for(ll i = 0; i < N*2; i++){
		if(belong[i] == -1){
			belong[i] = group.size();
			group.push_back(1);
			member.push_back({i});
			make_group(i, belong[i]);
		}
	}

	ll ans = 0;
	for(auto&& i : group) ans += i % 2;

	//アウトプット
	cout << ans/2;
	
	return 0;
}