sub compatible { 
    my ($s1, $s2) = @_; 
    $s1=~/\G_/gcs and $s2=~/./gcs or 
        $s1=~/./gcs and $s2=~/\G_/gcs or 
        return 0 until 
        $s1=~/\G\z/ or $s2=~/\G\z/; 
    1; } 
print(compatible("_8__3__19", "4_8___7__") ? "true\n" : "false\n");