Day 1: XY Tree
The next day: (X+5)(Y-5)
Day 3: (X+ 10)(Y- 10)
Day 4: (X+ 15)(Y- 15
)
Day 5 (X+20)(Y-20)
Day 6 (X+25)(Y-25)
Day 7 (X+30)(Y-30
therefore
Most kinds of trees