#include <iostream>
#include <stdio.h>

using namespace std;

int v[16010];
int main ()
{
	int n,k;
	freopen("transport.in", "r", stdin);
	freopen("transport.out", "w", stdout);
	
	scanf("%d%d", &n, &k);
    int cmin=0;

	for(int i=1; i<=n; i++)
	{
		scanf("%d\n", &v[i]);
		if(v[i] > cmin)
		{
			cmin=v[i];
		}
	}
	//printf("%d", cmin);
	int c=1,contor=0,s=v[1],i=1;

while(k)
	{
		if(s > cmin)
	    {
			cmin=s;
			s=v[i+1];
		}
		else
		{
			for( ; s<=cmin && i<=n; )
			{
				i++;
				s+=v[i];
				if(s <= k/2)
				{
					break;
					
				}
			}
		}
	k--;
    }
printf("%d", cmin);
	

	
	return 0;
}