<>;
for(<>){
	/ /;
	$x=$`/20+1|0;
	$y=$'/20+1|0;
	for$y($y-1..$y+1){
		for$x($x-1..$x+1){
			for(@{$_[$y][$x]}){
				if((@$_[0]-$`)**2+(@$_[1]-$')**2<400){
					goto a
				}
			}
		}
	}
	push@{$_[$y][$x]},[$`,$'];
	++$z;
	a:
}
print$z