Problem2422--数列-加减之和练习

2422: 数列-加减之和练习

Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 287  Solved: 214
[Status] [Submit] [Creator:]

Description

求2020-1+2-3+4-5+...±n的值（n为奇数时减，偶数时加）

Sample Input Copy 

100

Sample Output Copy 

2070

Source/Category

 基础B  
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