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Background

Description

计算等边三角形使用的火柴根数量（拓展04-输入总火柴根数量[有可能不能搭建一个完整的等边三角形]，计算层数）

Format

Input

Output

Samples

630

20

165

10

160

error

150

error

Limitation

1s, 1024KiB for each test case.