#include<cmath>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<cstdlib>
#define LL long long
using namespace std;
const int maxn=1000010;
int n,m,a[maxn];
void Init();
void Begin(){freopen("waterj.in","r",stdin);freopen("waterj.out","w",stdout);}
void End(){fclose(stdin);fclose(stdout);}

int main(){
    Begin();
    Init();
    //system("pause");
    End();
    return 0;
}
void Init(){
	scanf("%d%d",&n,&m);
	for(int i=1;i<=m;i++)scanf("%d",&a[i]);
	for(int i=m+1;i<=n;i++){
		int x;scanf("%d",&x);
		int _min=0x7f7f7f7f,k;
		for(int j=1;j<=m;j++){
			if(_min>a[j]){
				_min=a[j];k=j;
			}
		}
		a[k]+=x;
	}
	int ans=0;
	for(int i=1;i<=m;i++)ans=max(ans,a[i]);
	printf("%d\n",ans);
}