($X,$Y,$N,$F)=glob<>;
for$y(0..$Y){
	for$x(0..$X){
		$_[$Y-$y][$X-$x]=$F*($x+$y)
	}
}
for(<>){
	($dx,$dy,$c)=glob;
	for$y(0..$Y-$dy){
		for$x(0..$X-$dx){
			$_[$y][$x]-=$-=$_[$y][$x]-($_[$y+$dy][$x+$dx]+$c)
		}
	}
}
print$_[0][0]