Binary 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 1
s 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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