N,M = map(int,input().split())

num_list = list(map(int,input().split()))

i=0
cnt=0
total=0

while i < len(num_list):
    a = num_list[i]
    if i % 2 == 0:
        if cnt < M:
            total=0
            cnt=0
            
        else:
            print(total)
            total=0
            cnt=0
        i+=1
        continue
    else:
        cnt+=1
        total+=a
        i+=1