There are 10 vertical and horizontal squares on a plane. Each square is painted blue and green

<?php
{ 

    $field = array();
    for ($i = 0; $i < 12; $i++) {
        $field[] = str_split(rtrim(fgets(STDIN)));
    }
    fscanf(STDIN, '');
 
    $c = 0;
    for ($i = 0; $i < 10; $i++) {
        for ($j = 0; $j < 10; $j++) {
            if ($field[$i][$j] === '1') {
                dfs($field, array($i, $j));
                $c++;
            }
        }
    }
 
    echo "Number of islands: \n";
    echo $c . PHP_EOL;
}
 
function dfs(&$field, $s) {
    $stack = array($s);
    $dx = array(1, -1, 0, 0);
    $dy = array(0, 0, 1, -1);
    while (count($stack)) {
        $node = array_pop($stack);
        $field[$node[0]][$node[1]] = '0';
        for ($i = 0; $i < 4; $i++) {
            $nx = $node[1] + $dx[$i];
            $ny = $node[0] + $dy[$i];
            if (!isset($field[$ny][$nx]) || $field[$ny][$nx] === '0') {
                continue;
            }
            $stack[] = array($ny, $nx);
        }
    }
}
?>