#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;
int main(){
	freopen("deleteit.in","r",stdin);
	freopen("deleteit.out","w",stdout);
#if 1
	int n,m,q,i,x1,x2,y1,y2,x,y,sum;
	double m1;
	cin>>n>>m>>q;
	m1=m;
	x=m,y=n,sum=n*m;
	for(i=1;i<=q;i++){
		cin>>y1>>x1>>y2>>x2;
		x1++;x2++;y1++;y2++;
		if(x1>x2)swap(x1,x2);
		if(y1>y2)swap(y1,y2);
		if(x2<=x&&y2<y)sum-=(x2-x1+1)*(y2-y1+1);
		else if(x2<x)sum-=(x2-x1+1)*(y-y1+1);
		else if(y2==y){
			sum-=(x2-x1+1)*(y2-y1);
			if(x>=x1)sum-=min(x,x1)+1-x2;
		}
		if(sum>m){
			x=(sum-1)%m+1;
			y=ceil(sum/m1);
		}
	}
	cout<<sum;
	#endif
	return 0;
}