Binary [III]
View as PDFBinary Sequences [III]
The blurb for this problem is the same as Binary Sequences [I], save for the statement of the problem.
This set of problems is centered around a sequence generated in the following manner:
- Take all natural numbers in increasing order
- Replace each natural number with its binary representation
- Concatenate these into a single sequence
For example, the first 4 natural numbers generate the first 8 digits in the sequence: 11011100.
The first digit is 1, for 1. The next two are 10, for 2. The next two are 11, for 3, and the final three are 100, for 4.
In this third problem, we are actually looking at a modification of this sequence. For a jump size , we are only considering natural numbers divisible by
in our initial sequence. For example, for
, our number sequence is
3,6,9,12, which results in bit sequence 1111010011100. And are similarly looking for the total number of 1s present before an index , although rather than using an index, we are specifying the natural number we generate until. However, in this particular problem
will always be a power of two
So taking our , and generating for the first
possible natural numbers, the prefix sum string instead looks like:
1234455567888
as the first 13 digits.
Input
Input will consist of two space separated natural numbers and
.
Output
Output a single integer, representing the numbner of 1s in the sequence at or before (1-indexed) natural number , when using a jump of
.
Constraints
is always a power of 2.
Examples
Input
2 3
Output
4
Input
2 9
Output
4
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