#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
int main(){
	int N,M; cin >> N >> M;
	dsu uf(2 * N);
	while(M--){
		int a,b; cin >> a >> b;
		uf.merge(--a,--b);
	}
	int alone = 0;
	for(int i = 0; i < 2 * N; i++){
		if(uf.leader(i) != i) continue;
		alone += uf.size(i) % 2;
	}
	
	cout << alone / 2 << endl;
}