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

#include <algorithm>
#include <cstdio>

using std::max;

int main()
{
  int n = Size();
  int myNodeId = MyNodeId();
  int numberOfNodes = NumberOfNodes();
  int beginIndex = ((long long int)myNodeId * n) / numberOfNodes;
  int endIndex = ((long long int)(myNodeId + 1) * n) / numberOfNodes;
  //printf("node %d, b=%d, e=%d\n", myNodeId, beginIndex, endIndex);

  long long int myMax = 0;
  long long int mySum = 0;
  long long int myCurrentSum = 0;
  for (int i = beginIndex; i < endIndex; i++)
  {
    int value = ElementAt(i + 1);
    //printf("node %d index %d, value %d\n", myNodeId, i, value);
    mySum += value;
    myCurrentSum += value;
    if (myCurrentSum > myMax)
      myMax = myCurrentSum;
    if (myCurrentSum < 0)
      myCurrentSum = 0;
  }

  long long int totalMax = myMax;
  long long int totalCurrentSum = myCurrentSum;

  //printf("node %d myMax=%lld, mySum=%lld, myCurrentSum=%lld\n", myNodeId, myMax, mySum, myCurrentSum);

  if (myNodeId != 0)
  {
    PutLL(0, myMax);
    PutLL(0, mySum);
    PutLL(0, myCurrentSum);
    Send(0);
  }
  else
  {
    for (int nodeId = 1; nodeId < numberOfNodes; nodeId++)
    {
      PutLL(nodeId, totalCurrentSum);
      Send(nodeId);

      Receive(nodeId);
      long long nodeMax = GetLL(nodeId);
      long long nodeSum = GetLL(nodeId);
      long long nodeEndSum = GetLL(nodeId);

      if (nodeMax > totalMax)
        totalMax = nodeMax;
      
      //printf("node %d, totalCurrentSum=%lld nodeSum=%lld, nodeEndSum=%lld\n", nodeId, totalCurrentSum, nodeSum, nodeEndSum);
      totalCurrentSum = max(totalCurrentSum + nodeSum, nodeEndSum);
    }
    
  }

  if (myNodeId != 0)
  {
    Receive(0);
    myCurrentSum = GetLL(0);
    myMax = myCurrentSum;
    for (int i = beginIndex; i < endIndex; i++)
    {
      int value = ElementAt(i + 1);
      myCurrentSum += value;
      if (myCurrentSum > myMax)
        myMax = myCurrentSum;
      if (myCurrentSum < 0)
        break;
    }
    PutLL(0, myMax);
    Send(0);
  }
  else
  {
    for (int nodeId = 1; nodeId < numberOfNodes; nodeId++)
    {
      Receive(nodeId);
      long long nodeMax = GetLL(nodeId);
      if (nodeMax > totalMax)
        totalMax = nodeMax;
    }
    printf("%lld\n", totalMax);
  }

  return 0;
}