(?:
   (?(?{ !valid(0, 0, '1') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 0, 1, '1'); local $grid_v = $grid_v; substr($grid_v, 0, 1, '1'); }) |
   (?(?{ !valid(0, 0, '2') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 0, 1, '2'); local $grid_v = $grid_v; substr($grid_v, 0, 1, '2'); }) |
   (?(?{ !valid(0, 0, '3') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 0, 1, '3'); local $grid_v = $grid_v; substr($grid_v, 0, 1, '3'); }) |
   (?(?{ !valid(0, 0, '4') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 0, 1, '4'); local $grid_v = $grid_v; substr($grid_v, 0, 1, '4'); }) |
   (?(?{ !valid(0, 0, '5') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 0, 1, '5'); local $grid_v = $grid_v; substr($grid_v, 0, 1, '5'); }) |
   (?(?{ !valid(0, 0, '6') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 0, 1, '6'); local $grid_v = $grid_v; substr($grid_v, 0, 1, '6'); }) |
   (?(?{ !valid(0, 0, '7') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 0, 1, '7'); local $grid_v = $grid_v; substr($grid_v, 0, 1, '7'); }) |
   (?(?{ !valid(0, 0, '8') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 0, 1, '8'); local $grid_v = $grid_v; substr($grid_v, 0, 1, '8'); }) |
   (?(?{ !valid(0, 0, '9') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 0, 1, '9'); local $grid_v = $grid_v; substr($grid_v, 0, 1, '9'); })
)
(?:
   (?(?{ !valid(0, 1, '1') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 1, 1, '1'); local $grid_v = $grid_v; substr($grid_v, 9, 1, '1'); }) |
   (?(?{ !valid(0, 1, '2') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 1, 1, '2'); local $grid_v = $grid_v; substr($grid_v, 9, 1, '2'); }) |
   (?(?{ !valid(0, 1, '3') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 1, 1, '3'); local $grid_v = $grid_v; substr($grid_v, 9, 1, '3'); }) |
   (?(?{ !valid(0, 1, '4') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 1, 1, '4'); local $grid_v = $grid_v; substr($grid_v, 9, 1, '4'); }) |
   (?(?{ !valid(0, 1, '5') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 1, 1, '5'); local $grid_v = $grid_v; substr($grid_v, 9, 1, '5'); }) |
   (?(?{ !valid(0, 1, '6') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 1, 1, '6'); local $grid_v = $grid_v; substr($grid_v, 9, 1, '6'); }) |
   (?(?{ !valid(0, 1, '7') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 1, 1, '7'); local $grid_v = $grid_v; substr($grid_v, 9, 1, '7'); }) |
   (?(?{ !valid(0, 1, '8') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 1, 1, '8'); local $grid_v = $grid_v; substr($grid_v, 9, 1, '8'); }) |
   (?(?{ !valid(0, 1, '9') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 1, 1, '9'); local $grid_v = $grid_v; substr($grid_v, 9, 1, '9'); })
)
(?:
   (?(?{ !valid(0, 2, '1') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 2, 1, '1'); local $grid_v = $grid_v; substr($grid_v, 18, 1, '1'); }) |
   (?(?{ !valid(0, 2, '2') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 2, 1, '2'); local $grid_v = $grid_v; substr($grid_v, 18, 1, '2'); }) |
   (?(?{ !valid(0, 2, '3') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 2, 1, '3'); local $grid_v = $grid_v; substr($grid_v, 18, 1, '3'); }) |
.
.
.
   (?(?{ !valid(8, 8, '7') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 80, 1, '7'); local $grid_v = $grid_v; substr($grid_v, 80, 1, '7'); }) |
   (?(?{ !valid(8, 8, '8') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 80, 1, '8'); local $grid_v = $grid_v; substr($grid_v, 80, 1, '8'); }) |
   (?(?{ !valid(8, 8, '9') })x)(?{ local $grid_h = $grid_h; substr($grid_h, 80, 1, '9'); local $grid_v = $grid_v; substr($grid_v, 80, 1, '9'); })
)
(?{ $match_grid = $grid_h })