#include <bits/stdc++.h>

const long long NMAX = 2e5 + 5, INF = 1e17;

struct Node {
    long long maxLeftSum, maxRightSum, maxSubarraySum, maxi, sum;
} aint[4 * NMAX];

long long n, Q, e, a[NMAX], dp[40][2];
std :: vector < int > ans;

void Build(int node, int l, int r) {
    if (l == r) {
        aint[node].maxLeftSum = std :: max(a[l], 0LL);
        aint[node].maxRightSum = std :: max(a[l], 0LL);
        aint[node].maxSubarraySum = std :: max(a[l], 0LL);
        aint[node].maxi = a[l];
        aint[node].sum = a[l];

        return;
    }

    int mid = ((l + r) >> 1);

    Build(node * 2, l, mid);
    Build(node * 2 + 1, mid + 1, r);

    aint[node].maxLeftSum = std :: max(aint[node * 2].maxLeftSum, aint[node * 2].sum + aint[node * 2 + 1].maxLeftSum);
    aint[node].maxRightSum = std :: max(aint[node * 2 + 1].maxRightSum, aint[node * 2 + 1].sum + aint[node * 2].maxRightSum);
    aint[node].maxSubarraySum = std :: max(aint[node * 2 + 1].maxLeftSum + aint[node * 2].maxRightSum, std :: max(aint[node * 2].maxSubarraySum, aint[node * 2 + 1].maxSubarraySum));
    aint[node].maxi = std :: max(aint[node * 2].maxi, aint[node * 2 + 1].maxi);
    aint[node].sum = aint[node * 2].sum + aint[node * 2 + 1].sum;

    return;
}

/** void Update(int node, int l, int r, int k, int x) {
    if (l == r) {
        a[k] = x;

        aint[node].maxLeftSum = std :: max(a[k], 0LL);
        aint[node].maxRightSum = std :: max(a[k], 0LL);
        aint[node].maxSubarraySum = std :: max(a[k], 0LL);
        aint[node].sum = a[k];

        return;
    }

    int mid = ((l + r) >> 1);

    if (l <= k && k <= mid) {
        Update(node * 2, l, mid, k, x);
    }
    else {
        Update(node * 2 + 1, mid + 1, r, k, x);
    }

    aint[node].maxLeftSum = std :: max(aint[node * 2].maxLeftSum, aint[node * 2].sum + aint[node * 2 + 1].maxLeftSum);
    aint[node].maxRightSum = std :: max(aint[node * 2 + 1].maxRightSum, aint[node * 2 + 1].sum + aint[node * 2].maxRightSum);
    aint[node].maxSubarraySum = std :: max(aint[node * 2 + 1].maxLeftSum + aint[node * 2].maxRightSum, std :: max(aint[node * 2].maxSubarraySum, aint[node * 2 + 1].maxSubarraySum));
    aint[node].sum = aint[node * 2].sum + aint[node * 2 + 1].sum;

    return;
} **/

void Query(int node, int l, int r, int x, int y) {
    if (r < x || l > y) {
        return;
    }

    if (x <= l && r <= y) {
        e = std :: max(e, aint[node].maxi);
        ans.push_back(node);
        return;
    }

    int mid = ((l + r) >> 1);

    Query(node * 2, l, mid, x, y);
    Query(node * 2 + 1, mid + 1, r, x, y);

    return;
}

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

int main() {
    /// std :: ios_base :: sync_with_stdio(false);
    /// std :: cin.tie(nullptr);

    fin >> n >> Q;

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

    Build(1, 1, n);

    while (Q --) {
        int x, y;

        fin >> x >> y;

        /// Update(1, 1, n, k, x);

        ans.push_back(0);
        e = -INF;
        Query(1, 1, n, x, y);

        int m = ans.size() - 1;

        dp[0][0] = 0;
        dp[0][1] = 0;
        dp[0][2] = 0;

        for (int i = 1; i <= m; ++ i) {
            dp[i][0] = aint[ans[i]].maxLeftSum + dp[i - 1][1];
            dp[i][2] = aint[ans[i]].maxRightSum;
            dp[i][1] = std :: max(aint[ans[i]].sum + dp[i - 1][1], dp[i][2]);
        }

        long long Max = 0;

        for (int i = 1; i <= m; ++ i) {
            Max = std :: max(Max, dp[i][0]);
        }

        for (int i = 1; i <= m; ++ i) {
            Max = std :: max(Max, aint[ans[i]].maxSubarraySum);
        }

        if (Max == 0) {
            fout << e << "\n";
        }
        else {
            fout << Max << "\n";
        }

        ans.clear();
    }

    return 0;
}