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#include "maklib.h"
#include "message.h"

#include <algorithm>
#include <cstdio>
#include <vector>
#define LL long long
#define INF 1000000000
using namespace std;

int from, to, all, me, n;
vector<LL> pref;
vector<LL> DP;
LL best, maxiPref, maxiSuf, sum;

void solve() {
    int siz = to - from + 1;
    DP.resize(siz);
    pref.resize(siz);
    best = -INF;
    maxiPref = -INF;
    maxiSuf = -INF;
    sum = 0;
    for (int i = 0; i < siz; i++) {
        pref[i] = 0;
        if (i != 0) {
            pref[i] = pref[i - 1];
        }
        LL val = ElementAt(from + i + 1);
        pref[i] += val;
        DP[i] = val;
        if (i != 0 && DP[i - 1] > 0) {
            DP[i] += DP[i - 1];
        }
        maxiPref = max(maxiPref, pref[i]);
        best = max(best, DP[i]);
    }
    for (int i = 0; i < siz; i++) {
        LL suf = pref[siz - 1];
        if (i != 0) {
            suf -= pref[i - 1];
        }
        maxiSuf = max(maxiSuf, suf);
    }
    sum = pref[siz - 1];

    if (me != 0) {
        PutLL(0, best);
        PutLL(0, maxiPref);
        PutLL(0, maxiSuf);
        PutLL(0, sum);
        Send(0);
    }

}
void combine() {
    vector<LL> bests = {best};
    vector<LL> prefs = {maxiPref};
    vector<LL> sufs = {maxiSuf};
    vector<LL> sums = {sum};
    for (int cli = 1; cli < all; cli++) {
        Receive(cli);
        bests.push_back(GetLL(cli));
        prefs.push_back(GetLL(cli));
        sufs.push_back(GetLL(cli));
        sums.push_back(GetLL(cli));
    }
    LL ans = 0;
    ans = max(ans, best);
    for (int i = 0; i < all; i++) {
        ans = max(ans, bests[i]);
    }
    for (int a = 0; a < all; a++) {
        LL now = sufs[a];
        for (int b = a + 1; b < all; b++) {
            ans = max(ans, now + prefs[b]);
            now += sums[b];
        }
    }

    printf("%lld\n", ans);

}
int main() {
    all = NumberOfNodes();
    me = MyNodeId();
    n = Size();
    if (me >= n)
        return 0;
    all = min(all, n);
    int siz = n / all;
    from = siz * me;
    to = siz * (me + 1) - 1;
    if (me == all - 1) {
        to = n - 1;
    }
    solve();
    if (me == 0) {
        combine();
    }
    return 0;
}