4356: (2006广东省赛) Problem A Abundance 过剩数

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题目描述

An abundant number is a positive integer n for which Sigma(n) – 2n > 0,Where Sigma(n) is defined as the sum of all the divisors of n. And the quantity Sigma(n) – 2n is called abundance.

Given the range of n , you should find out the maximum abundance value  that can be reached. For example, if the range is [10,12] , then the only abundant number is 12 , and the maximum abundance value is Sigma(12) – 2 * 12 = 4.

输入

Input may contain several test cases. The first line is a positive integer, T (T <= 20) , the number of test cases below , Each test case contains two positive integers x , y , (1 <= x <= y  <= 1024) , indicating the range of n.

输出

For each test case, output the maximum abundance value that can be reached in the range of n. If there is no abundant number n in the range , simply output -1.

样例输入

3
1 1
10 12
1 1024

样例输出

-1
4
1208

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