$ar = file(__DIR__. '/level4_0.in');
$ar = array_map('trim', $ar);
array_splice($ar, 41, 1);
array_splice($ar, 0, 1);
$ar = array_map(function($row){
    $row = explode(' ', $row);
    $row = array_map('intval', $row);
    return $row;
}, $ar);

[
    [0, 5, 5, ..],
    [0, 5, 5, ..],
    ..
]

$found = [];
for ($row = 0; $row < count($ar); $row++) {
    for ($col = 0; $col < count($ar[$row]); $col++) {
        if ($ar[$row][$col] && (!$row || !$ar[$row - 1][$col])) {
            for ($c = $col; $c < count($ar[$row]); $c++) {
                if (!$ar[$row][$c]) {
                    break;
                }
            }
            if (($c - $col) > 2) {
                for ($r = $row; $r < count($ar); $r++) {
                    if (!$ar[$r][$col]) {
                        break;
                    }
                }
                if (($r - $row) > 2) {
                    $found[] = [
                        "row" => floor(($row + $r) / 2),
                        "col" => floor(($col + $c) / 2),
                    ];
                }
            }
            $col = $c;
        }
    }
}
echo "found:n";
foreach ($found as $node) {
    echo "{$node['row']}x{$node['col']}n";
}

found:
12x32
22x52
32x22
32x42
51x22
51x57
61x42
71x62
81x47