#include <bits/stdc++.h>

using namespace std;

ifstream fin("sequencequery.in");
ofstream fout("sequencequery.out");
struct Nod {
    long long secv;
    long long pref;
    long long suf;
    long long sum;
} a[400002];
int n, t, i, x, y;

/// creaza o reuniune a celor doua noduri
Nod Calc(Nod a, Nod b) {
    Nod c;
    c.sum = a.sum + b.sum;
    c.pref = max(a.pref, a.sum + b.pref);
    c.suf = max(b.suf,   b.sum + a.suf);
    c.secv = max(max(a.secv, b.secv), a.suf + b.pref);
    return c;
}

/// construieste
void build(int st, int dr, int nod) {
    if(st == dr) {
        fin >> a[nod].sum;
        a[nod].pref = a[nod].sum;
        a[nod].suf  = a[nod].sum;
        a[nod].secv = a[nod].sum;
        return;
    }

    int mij = st + (dr - st) / 2;
    build(st     , mij, nod * 2);
    build(mij + 1, dr , nod * 2 + 1);
    a[nod] = Calc(a[nod * 2], a[nod * 2 + 1]);
}

Nod query(int st, int dr, int nod) {
    if(x <= st && dr <= y) return a[nod];
    int mij = st + (dr - st) / 2;
    if(y <= mij)     return query(st     , mij, nod * 2);
    else if(x > mij) return query(mij + 1,  dr, nod * 2 + 1);
    else return Calc(query(st     , mij, nod * 2),
                     query(mij + 1,  dr, nod * 2 + 1));
}

int main() {
    fin >> n >> t;
    build(1, n, 1);
    while(t--) {
        fin >> x >> y;
        fout << query(1, n, 1).secv << "\n";
    }

    return 0;
}