from itertools import accumulate
n, q = map(int, input().split())
a = list(map(int, input().split()))
b = []
for i in a:
    for j in range(1, i+1):
        b.append(j)
print(b)
rui = list(accumulate(b, initial=0))
print(rui)

for i in range(q):
    x = int(input())
    ng = -1
    ok = len(rui)
    while abs(ok-ng) > 1:
        mid = (ok+ng)//2
        if rui[mid] >= x:
            ok = mid
        else:
            ng = mid
    if ok == len(rui):
        print(-1)
    else:
        print(ok)