>  Insert the values 2,1,4,5,9,3,6,7 into:
a. A probabilistic skip list (you can use this link to flip a virtual coin).

.

> for 2, T,   level = 1


.-2

> for 1, T,   level = 1

.-1-2

> for 4, T,   level = 1

.-1-2-4

> for 5, HHT, level = 3

.-------.
.-------.
.-1-2-4-5

> for 9, T,   level = 1

.-------.
.-------.
.-1-2-4-5-9

> for 3, T,   level = 1

.---------.
.---------.
.-1-2-3-4-5-9


> for 6, HHT, level = 3

.---------.-.
.---------.-.
.-1-2-3-4-5-6-9


> for 7, HT,  level = 2

.---------.-.
.---------.-.-.
.-1-2-3-4-5-6-7-9