Train like thetop 1%.

#include <bits/stdc++.h>
using namespace std;

// Compute prefix sums for O(1) range sum queries
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int n, q;
    if (!(cin >> n >> q)) return 0;

    vector<long long> pref(n + 1, 0);
    for (int i = 1; i <= n; ++i) {
        long long x; cin >> x;
        pref[i] = pref[i - 1] + x;
    }

    while (q--) {
        int l, r; cin >> l >> r;
        cout << (pref[r] - pref[l - 1]) << "\n";
    }
    return 0;
}