#include <iostream>
#include <fstream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#define ll long long
#define max 1000010
using namespace std;
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
ll n,m,q,all;
ll ln,col;
bool map[max];
inline ll read()
{
	char tmp=getchar();
	ll f=1,ans=0;
	while(tmp<'0'||tmp>'9')
	{
		if(tmp=='-')
			f=-f;
		tmp=getchar();
	}
	while(tmp>='0'&&tmp<='9')
	{
		ans=ans*10-'0'+tmp;
		tmp=getchar();
	}
	return ans*f;
}
ll work(ll x1,ll x2,ll y1,ll y2)
{
	ll tmp=0;
	if(ln<x1)
		return 0;
	if(ln>x2)
	{
		all-=(x2-x1+1)*(y2-y1+1);
		return 0;
	}
	x2=ln;
	all-=(x2-x1+1)*(y2-y1+1);
	if(col<y1) 
	{
		all+=y2-y1+1;
		return 0;
	}
	if(col>y2)
	{
		return 0;
	}
	y2=col;
	all+=y2-y1+1;
}
ll doit()
{
	ln=n,col=m;
	all=n*m;
	ll x1,x2,y1,y2;
	for(ll i=1;i<=q;i++)
	{
		x1=read();x2=read();y1=read();y2=read();
		work(x1+1,x2+1,y1+1,y2+1);
		ln=all/m;
		if(all%m) 
			ln++;
		col=all%m;
		if(col==0) 
			col=m;
	}
}
int main(int argc, char** argv)
{
	freopen("deleteit.in","r",stdin);
	freopen("deleteit.out","w",stdout);
	memset(map,false,sizeof(map));
	n=read();
	m=read();
	q=read();
	doit();
	printf("%lld\n",all); 
	//work();
	//com();
	return 0;
}