AT_abc439_c [ABC439C] 2026
Description
A positive integer $ n $ is called a **good integer** when it satisfies the following condition:
- There exists exactly one pair of integers $ (x,y) $ that satisfies $ 0 \lt x \lt y $ and $ x^2+y^2=n $ .
For example, when $ n=2026 $ , it can be verified that $ (x,y)=(1,45) $ is the only pair of integers that satisfies $ 0 \lt x \lt y $ and $ x^2+y^2=n $ . Thus, $ 2026 $ is a good integer.
You are given a positive integer $ N $ . Enumerate all good integers not exceeding $ N $ .
Input Format
The input is given from Standard Input in the following format:
> $ N $
Output Format
Let there be $ k $ good integers not exceeding $ N $ , and let $ (a_1, a_2, \dots, a_k) $ be the sequence of these integers in ascending order. Output the answer in the following format. (If $ k=0 $ , output the second line as an empty line.)
> $ k $ $ a_1 $ $ a_2 $ $ \dots $ $ a_k $
Explanation/Hint
### Sample Explanation 1
$ (x,y)=(1,2) $ is the only pair of integers that satisfies $ 0 \lt x \lt y $ and $ x^2+y^2=5 $ , so $ 5 $ is a good integer.
$ (x,y)=(1,3) $ is the only pair of integers that satisfies $ 0 \lt x \lt y $ and $ x^2+y^2=10 $ , so $ 10 $ is a good integer.
These are the only two good integers not exceeding $ N $ .
### Constraints
- $ 1 \leq N \leq 10^7 $
- $ N $ is an integer.