#include <cstdio>
#include <algorithm>

#define LL long long
#define NMAX 400007

using namespace std;

LL Ans, Sum, a[NMAX], b[NMAX], c[NMAX], d[NMAX];

void update(int Nod, int st, int dr, int Poz, int Val){
    if(st == dr){
        a[Nod] = b[Nod] = c[Nod] = d[Nod] = Val;
        return;
    }
    int med = (st + dr) >> 1;
    if(med >= Poz)
        update(Nod * 2, st, med, Poz, Val);
    else
        update(Nod * 2 + 1, med + 1, dr, Poz, Val);
    a[Nod] = max(a[Nod * 2], d[Nod * 2] + a[Nod * 2 + 1]);
    b[Nod] = max(b[Nod * 2 + 1], b[Nod * 2] + d[Nod * 2 + 1]);
    c[Nod] = max(max(c[Nod * 2], c[Nod * 2 + 1]), b[Nod * 2] + a[Nod * 2 + 1]);
    d[Nod] = d[Nod * 2] + d[Nod * 2 + 1];
}

void query(int Nod, int st, int dr, int x, int y){
    if(x <= st && dr <= y){
        if(Sum < 0)
            Sum = 0;
        Ans = max(Ans, max(Sum + a[Nod], c[Nod]));
        Sum = max(Sum + d[Nod], b[Nod]);
        return;
    }
    int med = (st + dr) >> 1;
    if(med >= x)
        query(Nod * 2, st, med, x, y);
    if(med < y)
        query(Nod * 2 + 1, med + 1, dr, x, y);
}

int main(){
    int n = 0, m = 0;
    freopen("sequencequery.in", "r", stdin);
    freopen("sequencequery.out", "w", stdout);
    scanf("%d %d", &n, &m);
    for(int i = 1; i <= n; ++i){
        int a = 0;
        scanf("%d", &a);
        update(1, 1, n, i, a);
    }
    for(int i = 1; i <= m; ++i){
        int x = 0, y = 0;
        Ans = -100000000;
        Sum = 0;
        scanf("%d %d", &x, &y);
        query(1, 1, n, x, y);
        printf("%lld\n", Ans);
    }
    return 0;
}