In programming, Photoshop and some other areas, the color always displayed in hexadecimal. The format is #RRGGBB. For example, red is #FF0000.
Now we define that a color RRGGBB is rigorously deeper than R'R'G'G'B'B' only when RR is less than R'R', GG is less than G'G' and BB is less than B'B'.
We give you several colors in hexadecimal, you have to pick up some colors and make them from deep to shallow. And you must pick as more as you can.
3 #BBCCDD #AABBCC #1064F9