Given an array of n integers and q queries, each query having a range from l to r. Find the maximum prefix-sum for the range l to r. NOTE: Assume indexing from 0.

Input: a[] = {-1, 2, 3, -5}
q = 2
l = 0, r = 3
l = 1, r = 3
Output: 4
5
Explanation:- The range (0, 3) in the 1st query has
[-1, 2, 3, -5], since it is prefix,
we have to start from -1. Hence, the
max prefix sum will be -1 + 2 + 3 = 4.
The range (1, 3) in the 1st query has
[2, 3, -5], since it is prefix, we
have to start from 2. Hence, the max
prefix sum will be 2 + 3 = 5.

Input:
The first line consists of an integer T i.e number of test cases. The first line of each test case consists of two integers n and q.Then next line consists of n spaced integers. The last line of each test case consists of q pairs of integers representing l and r.