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

#include <iostream>
#include <algorithm>
#include <cmath>

using namespace std;

long long Left_max[105];
long long Right_max[105];
long long Sum[105];
long long inf = 1000LL * 1000LL * 1000LL * 1000LL * 1000LL * 1000LL;

int main() 
{
	ios_base::sync_with_stdio(0);
	if (MyNodeId() == 0)
	{
		long long left_max = 0, right_max = 0, sum = 0;
		PutLL(1, 0LL);
		PutLL(1, 0LL);
		for (int i = 1; i < NumberOfNodes(); i++)
		{
			Receive(i);
			Left_max[i] = GetLL(i);
			Right_max[i] = GetLL(i);
			Sum[i] = GetLL(i);
			left_max = max(left_max, sum + Left_max[i]);
			sum += Sum[i];
			if (i + 1 < NumberOfNodes()) 
			{
				PutLL(i + 1, left_max);
				PutLL(i + 1, sum);
			}
		}
		sum = 0;
		PutLL(NumberOfNodes() - 1, 0LL);
		PutLL(NumberOfNodes() - 1, 0LL);
		Send(NumberOfNodes() - 1);
		for (int i = NumberOfNodes() - 1; i > 0; i--)
		{
			right_max = max(right_max, sum + Right_max[i]);
			sum += Sum[i];
			if (i - 1 >= 1)
			{
				PutLL(i - 1, right_max);
				PutLL(i - 1, sum);
				Send(i - 1);
			}
		}
		long long ans = 0;
		for (int i = 1; i < NumberOfNodes(); i++)
		{
			Receive(i);
			ans = max(ans, GetLL(i));
		}
		cout << ans << "\n";
		//if (left_i < right_i) cout << left_max + right_max << "\n";
		//else cout << sum << "\n";
	}
	else
	{
		int n = ceil(1.0 * GetN() / (NumberOfNodes() - 1));
		long long left_max = 0, right_max = 0, sum = 0;
		for (int i = (MyNodeId() - 1) * n; i < MyNodeId() * n and i < GetN(); i++)
		{
			//cout << i << " ";
			sum += GetTaste(i);
			left_max = max(left_max, sum);
		}
		sum = 0;
		for (int i = min(MyNodeId() * n, (int)GetN()) - 1; i >= (MyNodeId() - 1) * n; i--)
		{
			sum += GetTaste(i);
			right_max = max(right_max, sum);
		}
		PutLL(0, left_max);
		PutLL(0, right_max);
		PutLL(0, sum);
		Send(0);
		
		Receive(0);
		left_max = GetLL(0);
		long long left_sum = GetLL(0);
		right_max = GetLL(0);
		long long right_sum = GetLL(0);
		long long sum2 = sum;
		long long Sum = sum;
		sum = 0;
		long long mx = 0;
		//cout << left_max << " " << left_sum << " " << right_max << " " << right_sum << "\n";
		
		for (int i = (MyNodeId() - 1) * n; i < MyNodeId() * n and i < GetN(); i++)
		{
			mx = max(mx, left_max + sum2 + right_sum);
			//cout << left_max << " " << sum2 << "\n";
			//cout << i << "\n";
			sum2 -= GetTaste(i);
			sum += GetTaste(i);
			left_max = max(left_max, left_sum + sum);
		}
		
		sum = 0, sum2 = Sum;
		for (int i = min(MyNodeId() * n, (int)GetN()) - 1; i >= (MyNodeId() - 1) * n; i--)
		{
			mx = max(mx, right_max + sum2 + left_sum);
			//cout << right_max << " " << sum2 << "\n";
			sum2 -= GetTaste(i);
			sum += GetTaste(i);
			right_max = max(right_max, right_sum + sum);
		}
		PutLL(0, mx);
		Send(0);
	}
	
	
	return 0;
}