题目描述
Problem Statement
You are given an integer N.
Find the number of pairs of integers (x, y) that satisfy the following conditions, modulo 998244353.
-
$1 \leq x,y \leq N$.
-
x^2-y is a square number. (Assume 0 is also a square number.)
Input
Input is given from Standard Input in the following format:
N
Output
Print the answer.
Constraints
- $1 \leq N \leq 10^{12}$
- All values in input are integers.
Sample Input 1
3
Sample Output 1
2
We have the following two pairs.
-
x=1,y=1
-
x=2,y=3
Sample Input 2
10
Sample Output 2
8
Sample Input 3
10000000000
Sample Output 3
52583544
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
3
样例输出
2