#include <iostream>
#include <fstream>

#define cin inn
#define cout outt

using namespace std;

ifstream cin("transport.in");
ofstream cout("transport.out");




int main()
{
    int n,k,v[16001];

    cin>>n>>k;

    int s=0,mx=0;

    for(int i=0;i<n;i++)
    {
        cin>>v[i];
        s+=v[i];
        if(v[i]>mx) mx=v[i];
    }
    int mid=s/k;

    int sm=0;
    mx=0;
    for(int i=0;i<=n;i++)
    {
        if(sm>=mid)
        {
            if(mx<sm) mx=sm;
            sm=0;
        }
        if(i!=n) sm+=v[i];
    }
    sm=0;
    int mx2=0;
    for(int i=n-1;i>=-1;i--)
    {
        if(sm>=mid)
        {
            if(mx2<sm) mx2=sm;
            sm=0;
        }
        if(i!=-1) sm+=v[i];
    }
    cout<<mx>mx2?mx2:mx;
    return 0;
}