n,k=map(int,input().split())
l=list(map(int,input().split()))
def dfs(nl,nsum,nk):
    maxsum=0
    if nk==0:
        return nsum
    qd=[0]
    lenl=len(nl)
    for i in range(1,lenl-1):
        if lenl-i-1<=i and i%(lenl-i-1)==0  :
            qd.append(lenl-i)
    for i in qd:
        bl=nl.copy()
        bl.pop(i)
        maxsum=max(dfs(bl,nsum+nl[i],nk-1),maxsum)
    return maxsum
sum=dfs(l,0,k)
print(sum)