include

include

using namespace std;

const int N = 10010,M = 110; int a[N],b[M]; int m,n;

int main(){

cin >> n >> m;
for(int i=0;i<n;i++) cin >> a[i];
for(int i=0;i<m;i++) b[i] = a[i];
for(int i=m;i<n;i++){
	sort(b,b+m);
    b[0] += a[i];
}
sort(b,b+m);
cout << b[m-1];
return 0;

}