#include<stdio.h>
#define N 810
#define M 60010
int a[N],b[N],p[M],q[M],m,n,i;
void readd();
int main()
{
	readd();
	printf("%d",m/2);
	return 0;
}
void readd()
{
	freopen("poligon.in","rt",stdin);
	freopen("poligon.out","wt",stdout);
	scanf("%d%d",&n,&m);
	for(i=1;i<=n;i++)scanf("%d%d",&a[i],&b[i]);
	a[n+1]=a[1];b[n+1]=b[1];
	for(i=1;i<=n;i++)if(a[i]==a[i+1])for(;;);
	for(i=1;i<=m;i++)scanf("%d%d",&p[i],&q[i]);
}