18578번 - Jimp Numbers 다국어

A positive integer k is called a jimp number if there is exactly one triple of positive integers (a, b, c) such that a, b, and c are consecutive terms of an arithmetic progression (exactly in that order) and a² + b² + k = c².

Count the jimp numbers which are not greater than the given number n.

The only line contains a single integer n (1 ≤ n ≤ 10¹¹).

Print a single integer: the answer to the problem.