#3212. 数列求值
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ID: 3212
Type: Default
1000ms
256MiB
Tried: 0
Accepted: 0
Difficulty: 2
Uploaded By:
adler
Tags> 数列求值
Description
求 1−2+3−4...+n的值
Input Format
输入一个整数n
Output Format
输出一个整数
4
-2