#include <cstdio>
using namespace std;

int a[100001]={0};

int main(void)
{
	freopen("sent.in","r",stdin);
	freopen("sent.out","w",stdout);
	int i,n,m,temp,maxtemp=0,total=0;
	scanf("%d\n%d\n",&n,&m);
	m+=m;
	for (i=1;i<=m;i++)
	{
		scanf("%d",&temp);
		a[temp]++;
		if (temp>maxtemp)
			maxtemp=temp;
	}
	for (i=1;i<=maxtemp;i++)
	{
		if ((a[i]&1)==1)
			total++;
	}
	total-=2;
	total=(total+1)/2;
	if (total<0)
		total=0;
	printf("%d\n",total);
	fclose(stdin);
	fclose(stdout);
	return(0);
}