Help me in solving DNASTORAGE problem

My issue

could you please explain this problem

My code

# cook your dish here

Problem Link: DNASTORAGE Problem - CodeChef

@praveenbhandar
U have given a binary string which is a code . so u have to encode it which is following rules.

00 is replaced with A
01 is replaced with T
10 is replaced with C
11 is replaced with G

and then print the encoded string.