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#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#include "kanapka.h"
#include "message.h"

tuple<ll, ll, ll, ll> node_compute(ll b, ll e) {
    ll a, sum = 0, d = 0, best_mid = 0, best_left = 0, best_right = 0;
    for(ll i = b; i <= e; i++) {
	a = GetTaste(i);
	sum += a;
	best_left = min(best_left, sum);
	d = min(d + a, 0LL);
	best_mid = min(best_mid, d);
    }
    sum = 0;
    for(ll i = e; i >= b; i--) {
	a = GetTaste(i);
	sum += a;
	best_right = min(best_right, sum);
    }
    return make_tuple(sum, best_left, best_right, best_mid);
}

ll compute_all(ll n, ll s, ll l, ll r, ll m) {
    vector<ll> sum(n), bl(n), br(n);
    sum[0] = s; bl[0] = l; br[0] = r;
    ll cnt = 1, best = m, suma = s;
    while(cnt < n) {
	ll id = Receive(-1);
	sum[id] = GetLL(id);
	suma += sum[id];
	bl[id] = GetLL(id);
	br[id] = GetLL(id);
	best = min(best, GetLL(id));
	cnt++;
    }

    for(ll b = 0; b < n - 1; b++) {
	ll x = br[b];
	for(ll e = b + 1; e < n; e++) {
	    best = min(best, x + bl[e]);
	    x += sum[e];
	}
    }

    return suma - best;
}
    

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    ll n = GetN();
    ll num_nodes = NumberOfNodes();
    ll node_id = MyNodeId();
    ll part_size = (n + (num_nodes - n%num_nodes)) / num_nodes;
    ll used_nodes = (n + part_size - 1) / part_size;

    if(node_id >= used_nodes) return 0;

    ll sum, bl, br, bm;
    tie(sum, bl, br, bm) = node_compute(node_id * part_size, min(n - 1, (node_id + 1) * part_size - 1));

    if(node_id != 0) {
	PutLL(0, sum);
	PutLL(0, bl);
	PutLL(0, br);
	PutLL(0, bm);
	Send(0);
    }
    else {
    cout << compute_all(used_nodes, sum, bl, br, bm) << endl;
    }
}