Time limit: 5000ms
Memory limit: 256mb

Description:
Given a sorted array A of positive integers (in ascending order),  please perform Q queries: what is the sum of elements in range [a, b]?
Hint: a linear scan may exceed the time limit in some testcases. Please use the binary search. 

-------------------------Copy the following code, complete it and submit-------------------------


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*/

#include <stdio.h>
#include <stdlib.h>

#define MAX_LEN 1024 * 1024 * 10
#define MAX_QUERIES 1024 * 100

int range_sum_query(int a[], int n, int l, int r) {
  // WRITE YOUR CODE HERE
  // HINT: use binary search to find the boundry
}

// DO NOT MODIFY THE CODE BELOW
int main() {
  int n, q;
  int left[MAX_QUERIES];
  int right[MAX_QUERIES];
  int result;
  int i;
  int *a;

  a = (int *)malloc(MAX_LEN * sizeof(int));
  scanf("%d", &n);
  scanf("%d", &q);

  for (i = 0; i < n; i++)
    scanf("%d", &a[i]);

  for (i = 0; i < q; i++) {
    scanf("%d %d", &left[i], &right[i]);
  }

  for (i = 0; i < q; i++) {
    result = range_sum_query(a, n, left[i], right[i]);
    printf("%d\n", result);
  }
  free(a);
  return 0;
}
-----------------------------------------End of Code-----------------------------------------

Input:
First line is two integers N and Q;
Second line is the array of N positive integers which has been sorted in ascending order;
Then Q lines follows: each line uses two integers a and b to represent a range [a, b].
0 <= N <= 10^7, 0 <= Q <= 10^5

Output:
The output has Q lines. The i-th line is the answer of the i-th range sum query.
If there is no elements in the input range, please return 0. 

Sample Input 1:
4 3
1 3 5 8
4 6
2 3
6 7

Sample Output 1:
5
3
0