#include <iostream>
#include <fstream>

using namespace std;


ifstream fin("sequencequery.in");
ofstream fout("sequencequery.out");


const int N = 1e5, MAX = 1e5;
int n, m;
int v[N+1];
long long s[N+1];

struct arbore
{
    long long sum;
    long long st;
    long long dr;
}
aint[4*N+1];


void build(int nod, int st, int dr)
{
    if (st == dr)
    {
        aint[nod].sum = aint[nod].st = aint[nod].dr = v[st];
        return;
    }
    int mid = (st+dr)/2;
    build(nod<<1, st, mid);
    build(nod<<1 | 1, mid+1, dr);
    ///sum
    aint[nod].sum = max( max(aint[nod<<1].sum, aint[nod<<1 | 1].sum) , aint[nod<<1].dr + aint[nod<<1 | 1].st );
    ///st
    aint[nod].st = max( aint[nod<<1].st, s[mid]-s[st-1] + aint[nod<<1 | 1].st );
    ///dr
    aint[nod].dr = max( aint[nod<<1 | 1].dr, s[dr]-s[mid] + aint[nod<<1].dr );
}


arbore query(int nod, int st, int dr, int L, int R)
{
    if (R < st || dr < L)
        return {-MAX-1, -MAX-1, -MAX-1};
    if (L <= st && dr <= R)
        return aint[nod];

    int mid = (st+dr)/2;
    arbore left = query(nod<<1, st, mid, L, R);
    arbore right = query(nod<<1 | 1, mid+1, dr, L, R);

    arbore ret;
    ret.sum = max( max(left.sum, right.sum) , left.dr + right.st );
    ret.st = max( left.st, s[mid]-s[st-1] + right.st );
    ret.dr = max( right.dr, s[dr]-s[mid] + left.dr );
    return ret;
}


int main()
{
    fin >> n >> m;


    for (int i = 1; i <= n; i++)
        fin >> v[i];

    for (int i = 1; i <= n; i++)
        s[i] = v[i] + s[i-1];

    build(1, 1, n);


    for (int i = 1; i <= m; i++)
    {
        int x, y;
        fin >> x >> y;
        arbore rasp = query(1, 1, n, x, y);
        fout << rasp.sum << '\n';
    }


    return 0;
}