#include<stdio.h>
#include<algorithm>
using namespace std;
int n,m,q;
int re,ry,rx;
int X1,X2,Y1,Y2;
void delete1(int x1,int y1,int x2,int y2)
{
	if(x1<=rx)
		re-=((min(rx,x2)-x1+1)*(y2-y1+1));
	if((x1<=rx+1)&&(x2>=rx+1))
		if(y1<=ry)
			re-=(min(ry,y2)-y1+1);
	rx=re/m;
	ry=re%m;
}
void read()
{
	scanf("%d%d%d%d",&X1,&Y1,&X2,&Y2);
		delete1(X1+1,Y1+1,X2+1,Y2+1);
}
int main()
{
	freopen("deleteit.in","r",stdin);
	freopen("deleteit.out","w",stdout);
	scanf("%d%d%d",&n,&m,&q);
	re=n*m,rx=n,ry=0;
	while(q--)
		read();
	printf("%d",re);
	return 0;
}