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#include "maklib.h"
#include "message.h"
#include <algorithm>
#include <iostream>
using namespace std;

int main() {
	int nodesNumber = NumberOfNodes();	

	if (nodesNumber >= Size()) {
		if (MyNodeId() > 0) {			
			return 0 ;
		} else {		
			nodesNumber = 1;
		}
	}


	long long sum, leftSum, rightSum, partSum = 0;


	int partSize = Size() / nodesNumber;

	int start = (MyNodeId() * partSize) + 1;
	int end = start + partSize;

	if (MyNodeId() == nodesNumber - 1) {
		end = Size() + 1;
	}

	//cout << start  << "-" <<  end << endl;	
		

	long long maxSum = ElementAt(start), maxCurrent = ElementAt(start);

        long long maxLeftSum = ElementAt(start), currentLeftSum = ElementAt(start);

	partSum = ElementAt(start);
	for (int i = start + 1; i< end; ++i ) {
		int element = ElementAt(i);

		if (maxCurrent + element >  element) {
			maxCurrent = maxCurrent + element;
		} else {
			maxCurrent = element;
		}

		if (maxCurrent > maxSum) {
			maxSum = maxCurrent;
		}

		currentLeftSum += element;

		if (currentLeftSum > maxLeftSum) {
			maxLeftSum = currentLeftSum;
		}	

		partSum += element;	

	}

       long long maxRightSum = ElementAt(end -1), currentRightSum = ElementAt(end -1);
	for (int i = end -2; i >= start; --i) {
		int element = ElementAt(i);		

		currentRightSum += element;

		if (currentRightSum > maxRightSum) {
			maxRightSum = currentRightSum;
		}
	}


	sum = maxSum;
	leftSum = maxLeftSum;
	rightSum = maxRightSum;


  	if (MyNodeId() > 0) {
		PutLL(0, partSum);
    		PutLL(0, sum);
    		PutLL(0, leftSum);
    		PutLL(0, rightSum);		
    		Send(0);
  	} else {

		long long partResults[nodesNumber];
		long long subResults[nodesNumber];
		long long subResultsLeft[nodesNumber];
		long long subResultsRight[nodesNumber];

		partResults[0] = partSum;
		subResults[0] = sum;
		subResultsLeft[0] = leftSum;
		subResultsRight[0] = rightSum;

		//cout << "0: " << subResults[0] << " " << subResultsLeft[0] << " " << subResultsRight[0] << endl;

    		for (int i = 1; i < nodesNumber; ++i) {
      			Receive(i);

			partResults[i] = GetLL(i);
			subResults[i] = GetLL(i);
			subResultsLeft[i] = GetLL(i);
			subResultsRight[i] = GetLL(i);

			//cout << i << ": " << partResults[i] << " " << subResults[i] << " " << subResultsLeft[i] << " " << subResultsRight[i] << endl;
    		}

			//cout << endl;
		for (int i =0; i < nodesNumber; ++i) {
			if (subResults[i] > sum) {
				sum = subResults[i];
			}
			
		}		
		
		for (int i =1; i < nodesNumber; ++i) {
			if (subResultsRight[i-1] + partResults[i] > subResultsRight[i]) {
				subResultsRight[i] = subResultsRight[i-1] + partResults[i];
			}


			if (subResultsRight[i -1] + subResultsLeft[i] > sum) {
				sum = subResultsRight[i -1] + subResultsLeft[i];
			}

			//cout << i << ": " << partResults[i] << " "  << subResults[i] << " " << subResultsLeft[i] << " " << subResultsRight[i] << endl;
		}
		

		cout << sum << endl;


  	}
}