题意:
很不好描述的题意...看了Hint再看Description才理解的.
You've got a positive integer sequence a1, a2, ..., an. All numbers in the sequence are distinct.
Let's fix the set of variables b1, b2, ..., bm. Initially each variable
bi
(1 ≤ i ≤ m) contains the value of zero. Consider the following sequence, consisting of
n operations.
有n个数, 作为一组等式的得数.
有m个变量, 可以视为容器.
The first operation is assigning the value of a1 to some variable
bx
(1 ≤ x ≤ m). Each of the following
......
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