题目描述

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输入格式

As shown in the PDF.

输出格式

As shown in the PDF

样例

3 
1 1 
1

9

提示

There are 4 nice subsets: (1,2)(1,3) (1,2)(2,3) (1,3)(2,3) (1,2)(1,3)(2,3) Their values are 2,2,2,3 respectively. 录题人:chimp