201251: [AtCoder]ARC125 B - Squares
Memory Limit:1024 MB
Time Limit:2 S
Judge Style:Text Compare
Creator:
Submit:0
Solved:0
Description
Score : $500$ points
Problem Statement
You are given an integer $N$. Find the number of pairs of integers $(x, y)$ that satisfy the following conditions, modulo $998244353$.
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$1 \leq x,y \leq N$.
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$x^2-y$ is a square number. (Assume $0$ is also a square number.)
Constraints
- $1 \leq N \leq 10^{12}$
- All values in input are integers.
Input
Input is given from Standard Input in the following format:
$N$
Output
Print the answer.
Sample Input 1
3
Sample Output 1
2
We have the following two pairs.
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$x=1,y=1$
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$x=2,y=3$
Sample Input 2
10
Sample Output 2
8
Sample Input 3
10000000000
Sample Output 3
52583544