Ques : Given a binary string of length n. Output number of unique numbers that can be generated with the decimal representation of all the subsequences of the given binary string.

Sample 1 : 
String :  '011'
output :  3 
explanation : [0,1,3]

Sample 2 : 
String : '101'
Output : 5
Explanation : [0,1,2,3,5]