from bisect import bisect_left as left

N,Q = map(int,input().split())
a = list(map(int,input().split()))
b = []
sb = [0]
for i in range(N):
    for j in range(a[i]):
        b.append(j+1)
        sb.append(sb[-1]+b[-1])

for _ in range(Q):
    s = int(input())
    if sb[-1] < s:
        print(-1)
    else:
        print(left(sb,s))