Reversals and Sums

Given an array of n integers, you have to process following operations: - reverse a subarray - calculate the sum of values in a subarray Input The first input line has two integers n and m: the size of the array and the number of operations. The array elements are numbered 1,2,\dots,n. The next line as n integers x_1,x_2,\dots,x_n: the contents of the array. Finally, there are m lines that d