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#include "kanapka.h"
#include "message.h"

#include <algorithm>
#include <iostream>
#include <thread>
#include <chrono>

using namespace std;

//long long GetTaste(long long i);

long long elem_from, elem_to;
long long len;

long long get(long long n) {
    return GetTaste(n+elem_from-1);
}

int main() {
    int nodes = NumberOfNodes();
    int myNode = MyNodeId();

   // std::this_thread::sleep_for(std::chrono::milliseconds{myNode*100});

    auto N = GetN();

    elem_from = N*myNode/nodes;
    elem_to = N*(myNode+1)/nodes;
    len = elem_to-elem_from;

    std::vector<long long> pref, suf;
    pref.resize(len+2, 0);
    suf.resize(len+2, 0);


    long long sum = 0;
    for(auto i = 1; i <= len; ++i) {
        sum += get(i);
        pref[i] = std::max(pref[i-1], sum);
    }

    sum = 0;
    for(auto i = len; i >= 1; --i) {
        sum += get(i);
        suf[i] = std::max(suf[i+1], sum);
    }

    long long max_both = 0;
    for(auto i = 0; i <= len; ++i) {
        max_both = std::max(max_both, pref[i] + suf[i+1]);
    }

//    printf("0\t");
//    for(auto i = 1; i <= len; ++i) {
//        printf("%lld\t", get(i));
//    }
//    printf("0\n");
//    printf("\n");
//
//    for(auto i = 0; i <= len+1; ++i) {
//        printf("%lld\t", pref[i]);
//    }
//    printf("\n");
//    for(auto i = 0; i <= len+1; ++i) {
//        printf("%lld\t", suf[i]);
//    }
//    printf("\n");
//    printf("\n");

    PutLL(0, sum);
    PutLL(0, pref[len]);
    PutLL(0, suf[1]);
    PutLL(0, max_both);
    Send(0);

    if (myNode == 0) {
        //std::this_thread::sleep_for(std::chrono::milliseconds{1000});
        std::vector<long long> block_sums, block_prefix, block_suffix, block_max_both_sides;

        block_sums.push_back(0);
        block_prefix.push_back(0);
        block_suffix.push_back(0);
        block_max_both_sides.push_back(0);

        for (auto i = 1; i <= nodes; ++i) {
            Receive(i-1);
            block_sums.push_back(GetLL(i-1));
            block_prefix.push_back(GetLL(i-1));
            block_suffix.push_back(GetLL(i-1));
            block_max_both_sides.push_back(GetLL(i-1));

//            printf("[%d] Sum: %lld pref: %lld suf: %lld both: %lld\n", i, block_sums[i], block_prefix[i], block_suffix[i], block_max_both_sides[i]);
        }

        block_sums.push_back(0);
        block_prefix.push_back(0);
        block_suffix.push_back(0);
        block_max_both_sides.push_back(0);

        std::vector<long long> pref, suf, sum_prefix, sum_suffix;
        pref.resize(nodes+2, 0);
        suf.resize(nodes+2, 0);
        sum_prefix.resize(nodes+2, 0);
        sum_suffix.resize(nodes+2, 0);


        for (auto i = 1; i <= nodes; ++i) {
            pref[i] = std::max(pref[i-1], sum_prefix[i-1] + block_prefix[i]);

            sum_prefix[i] = sum_prefix[i-1] + block_sums[i];
        }

        for (auto i = nodes; i >= 1; --i) {
            suf[i] = std::max(suf[i+1], sum_suffix[i+1] + block_suffix[i]);

            sum_suffix[i] = sum_suffix[i+1] + block_sums[i];
        }

//        printf("PREF:\n");
//        for (auto i = 0; i <= nodes+1; ++i) {
//            printf("%lld\t", pref[i]);
//        }
//        printf("\n\nSUF:\n");
//        for (auto i = 0; i <= nodes+1; ++i) {
//            printf("%lld\t", suf[i]);
//        }
//        printf("\n");


//        printf("FINISH_AT:\n");
        long long result = 0;

        for (auto i = 0; i <= nodes; ++i) {
            auto finish_from_left_to_i = pref[i] + suf[i+1];

            result = std::max(result, finish_from_left_to_i);
//            printf("%lld\t", finish_from_left_to_i);
        }
//        printf("\n\n");

//        printf("BOTH AT:\n");
        for (auto i = 1; i <= nodes; ++i) {
            auto finish_both_at_i = sum_prefix[i-1] + block_max_both_sides[i] + sum_suffix[i+1];

            result = std::max(result, finish_both_at_i);
//            printf("%lld\t", finish_both_at_i);
        }
//        printf("\n\n");

        printf("%lld\n", result);
//        max_prefix = 0;
//        for (auto i = 0; i < nodes-1; ++i) {
//            max_prefix = std::max(max_prefix, block_sums[i]+block_prefix[i+1]);
//        }
//
//        max_suffix = 0;
//        for (auto i = nodes-1; i > 0; --i) {
//            max_suffix = std::max(max_suffix, block_sums[i]+block_suffix[i-1]);
//        }
//
//        printf("%lld\n", max_prefix+max_suffix);
    }
    return 0;
}