from bisect import bisect_left

n, q = map(int, input().split())
A = list(map(int, input().split()))
cum = [0]
for a in A:
    for i in range(1, a + 1):
        cum.append(cum[-1] + i)

for _ in range(q):
    S = int(input())
    if S > cum[-1]:
        print(-1)
    else:
        print(bisect_left(cum, S))