($n,$b)=<>=~/\d+/g;

for(<>){
    ($x[$i],$y[$i],$p[$i])=/\d+/g;
    ++$i;
}

%h=();
for$i(0..$n-1){
    $h{$x[$i]}=1;
}
@xs=sort{$a-$b}keys%h;

%h=();
for$i(0..$n-1){
    $h{$y[$i]}=1;
}
@ys=sort{$a-$b}keys%h;

for$y(@ys){
    for$x(@xs){
	for$i(0..$n-1){
	    if($x<=$x[$i]&&$y<=$y[$i]){
		$v{$x,$y}++;
		$w{$x,$y}+=$p[$i];
	    }
	}
    }
}

for$y0(@ys){
    for$y1(@ys){
	for$x0(@xs){
	    for$x1(@xs){
		if($w{$x0,$y0}-$w{$x0,$y1}-$w{$x1,$y0}+$w{$x1,$y1}<=$b){
		    if($r<$v{$x0,$y0}-$v{$x0,$y1}-$v{$x1,$y0}+$v{$x1,$y1}){
			$r=$v{$x0,$y0}-$v{$x0,$y1}-$v{$x1,$y0}+$v{$x1,$y1};
		    }
		}
	    }
	}
    }
}

print$r;