import sys
input = sys.stdin.readline
from bisect import *

N, Q = map(int, input().split())
A = list(map(int, input().split()))
acc = [0]
s_acc = [0]

for Ai in A:
    acc.append(acc[-1]+Ai)
    s_acc.append(s_acc[-1]+Ai*(Ai+1)//2)

for _ in range(Q):
    S = int(input())
    
    if s_acc[-1]<S:
        print(-1)
        continue
    
    i = bisect_left(s_acc, S)
    l, r = 1, A[i-1]
    
    while l<=r:
        m = (l+r)//2
        
        if m*(m+1)//2>=S-s_acc[i-1]:
            r = m-1
        else:
            l = m+1
    
    print(acc[i-1]+l)