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弱鸡还是弱鸡啊最简单的背包问题——。——！

1) 问题描述：

假设有一个能装入总体积为 T 的背包和 n 件体积分别为 W1，W2，···，Wn 的物品，能否从 n 件物品中挑选若干件恰好装满背包，即使 W1+W2+···+Wn=T，要求找出所有满足上述条件的解。例如：当 T=10，共 6 件物品，物品的体积为{1，2，3，4，5，8}，那么可找到下列 4 组解：（1，2，3，4）、（1，4，5）、（2，3，5）、（2、8）。

K. 2018

Given a,b,c,d, find out the number of pairs of integers (x,y) where a ≤ x ≤ b,c ≤ y ≤ d and x·y is a multiple of 2018.

B. Higher h-index

The h-index of an author is the largest h where he has at least h papers with citations not less than h.
Bobo has no papers and he is going to publish some subsequently. If he works on a paper for x hours, the
paper will get (a·x) citations, where a is a known constant. It’s clear that x should be a positive integer.
There is also a trick – one can cite his own papers published earlier.

Given Bobo has n working hours, find the maximum h-index of him.