Collect and sort square numbers in ascending order from three lists

var lists = [
  [3,4,34,25,9,12,36,56,36],
  [2,8,81,169,34,55,76,49,7],
  [75,121,75,144,35,16,46,35],
]
 
say lists.flat.grep{.is_square}.sort

Output:

[4, 9, 16, 25, 36, 36, 49, 81, 121, 144, 169]