fn main
[
	var lines := list_break_to_lines(read_lazy(h[0]));
	const x := len(lines[0]);
	const y := len(lines);
	var removed := 0;
again:
	var adj := array_fill(0, [ x, y ]);
	for i := 0 to x do [
		for j := 0 to y do [
			if lines[j][i] = '@' then [
				for k := -1 to 2 do [
					for l := -1 to 2 do [
						if i + k >= 0, i + k < x, j + l >= 0, j + l < y then
							adj[i + k, j + l] += 1;
					]
				]
			]
		]
	]
	var did_something := false;
	for i := 0 to x do [
		for j := 0 to y do [
			if lines[j][i] = '@' then [
				if adj[i, j] <= 4 then [
					removed += 1;
					lines[j][i] := '.';
					did_something := true;
				]
			]
		]
	]
	if did_something then
		goto again;
	write(h[1], ntos(removed) + nl);
]