Subarray Sum Queries Using Prefix Sums

This problem requires you to efficiently answer multiple queries on the sum of a subarray of an integer array using the prefix sums technique.

Given an array \( A[1 \ldots n] \), the prefix sums array \( P \) is defined by the equation:

\( P[i] = \sum_{j=1}^{i} A[j] \) with \( P[0] = 0 \).

For each query specified by two indices \( l \) and \( r \) (where indices are 1-indexed), the subarray sum is computed as:

\( \text{Sum} = P[r] - P[l-1] \).

Your task is to process the queries and output the corresponding subarray sums.

inputFormat

The first line contains two integers \( n \) and \( q \) representing the number of elements in the array and the number of queries, respectively.

The second line contains \( n \) space-separated integers representing the elements of the array.

Each of the following \( q \) lines contains two integers \( l \) and \( r \), denoting the range (inclusive) for a subarray sum query. It is guaranteed that \( 1 \leq l \leq r \leq n \).

outputFormat

For each query, output a single integer representing the sum of the subarray from index \( l \) to \( r \) (inclusive). Each result should be printed on a new line.

## sample

6 3
1 2 3 4 5 6
1 3
2 5
1 6

6
14
21

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