题解 | #【模板】静态区间和（前缀和）#

#include <iostream>
#include <queue>
#include <map>
#include <set>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <iomanip>
#include <stack>
#include <numeric>
#include <ctime>
#include <string>
#include <bitset>
#include <unordered_map>
#include <unordered_set>

using namespace std;
using ll = long long;
const ll N = 1e6 + 5, mod = 1e9 + 7, inf = 0x3f3f3f3f;

ll n, q, a[N];

void solve() {
    cin >> n >> q;

    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        a[i] += a[i - 1];
    }

    while (q--) {
        int l, r;
        cin >> l >> r;
        cout << a[r] - a[l - 1] << '\n';
    }
}

int main() {
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);

    int t = 1;
    //cin >> t;

    while (t--) {

        solve();

    }

    return 0;
}