Binary [II]
View as PDFBinary Sequences [II]
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 second problem, we want to find the number of 1s that occur in the sequence at or before index . So if we kept a running total of the prefix sums of our sequence, we'd get:
12234555
as the first 8 digits.
Input
Input will consist of a single natural number .
Output
Output a single integer, representing the numbner of 1s in the sequence at or before (1-indexed) index .
Constraints
Examples
Input
3
Output
2
Input
4
Output
3
Input
8
Output
5
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