from bisect import bisect_left
N,Q = map(int,input().split())
A = list(map(int,input().split()))
B = []
for i in range(N):
    B += list(range(1,A[i]+1))
C = [0]*len(B)
C[0] = B[0]
for i in range(1,len(B)):
    C[i] = C[i-1]+B[i]
for _ in range(Q):
    s = int(input())
    ind = bisect_left(C,s)
    if ind==len(B):
        print(-1)
    else:
        print(ind+1)