from bisect import *

N, Q = map(int, input().split())
A = list(map(int, input().split()))
L = []
for a in A:
    L.extend(list(range(1, a + 1)))
M = len(L)
Ac = [0] * (M + 1)
for i in range(M):
    Ac[i + 1] = Ac[i] + L[i]

for i in range(Q):
    s = int(input())
    ind = bisect_left(Ac, s)
    if ind == M + 1:
        print(-1)
    else:
        print(ind)