#include <iostream>
#include <fstream>
using namespace std;

ifstream fin("transport.in");
ofstream fout("transport.out");

int main()
{
    int n,k,S = 0,a, maxim = -1;
    fin>>n>>k;
    S = 0;
    for(int i = 1; i<=n; i++)
    {
        fin>>a;
        if(i == 1)
            {
                maxim = a;
                k--;
            }
        if(k>1 && i>1)
        {
            if(a>maxim)
            {
                maxim = a;
                k--;
            }
            else
            {
                if((S + a) <= maxim)
                {
                    S = S + a;
                }
                else
                {
                    S = a;
                    k--;
                }
            }
        }
        else
            if(k==1)
            S = S+a;
        if(S > maxim)
            maxim = S;

    }
    fout<<maxim;
}