#include<iostream>
using namespace std;
int main()
{
	bool a[240][240]={0};
	int b=0,c=0,num=0, select=0,cnt=0,x1=0,y1=0,x2=0,y2=0;
    //b,c为田的大小，num为耕田次数，select为限制输入耕田坐标的次数条件
	cin >> b>>c>>num;
	while (num != select)
	{
		select++;
		cin >> x1>>y1>>x2>>y2;
		for (int i = x1-1; i < x2; i++)
		{
			for (int j = y1-1; j < y2; j++)
			{
				a[i][j] = 1;
			}
		}
	}
	for (int i = 0; i < b; i++)
	{
		for (int j = 0; j < c; j++)
		{
			//cout << a[i][j];
			if (a[i][j] == 1)
			{
				cnt++;
			}
		}
		cout << endl;
	}
	cout << endl;
	cout << cnt;

}

}