import bisect
N,Q=map(int,input().split())
A=list(map(int,input().split()))

P=[]
for a in A:
    P+=list(range(1,a+1))

S=[0]
for p in P:
    S.append(S[-1]+p)

for i in range(Q):
    x=int(input())
    k=bisect.bisect_left(S,x)

    if k==len(S):
        print(-1)
    else:
        print(k)