解

#include <bits/stdc++.h>
using namespace std;
int n, m, x, s[100005];
int main() {
    cin >> n >> m;
    for(int i = 1; i <= n; i++) {
        cin >> x;
        s[i] = s[i-1] + x;//区间和
    }
    for(int i = 1; i <= m; i++) {
        int l, r;
        cin >> l >> r;
        cout << s[r] - s[l-1] << endl; 
    }
    return 0;
}