1 #include<bits/stdc++.h>
2 using namespace std;
3 const int maxn = 1000 + 5;
4 int C[maxn], n;
5
6 int lowbit(int x) {return x & -x;}
7
8 int sum(int x) {
9 int ret = 0;
10 while(x) {
11 ret += C[x]; x -= lowbit(x);
12 }
13 return ret;
14 }
15
16 void add(int x, int d) {
17 while(x <= n) {
18 C[x] += d; x += lowbit(x);
19 }
20 }
21
22 int get_sum(int L, int R) {
23 return sum(R) - sum(L-1);
24 }
25
26 int main() {
27 int q, d;
28 while(cin >> n >> q) {
29 memset(C, 0, sizeof(C));
30 for (int i = 1; i <= n; ++i) {
31 cin >> d;
32 add(i, d);
33 }
34 int qL, qR;
35 while(q--) {
36 cin >> qL >> qR;
37 cout << get_sum(qL, qR) << endl;
38 }
39 }
40
41 return 0;
42 }
