import bisect
import itertools

def main():
    import sys
    input = sys.stdin.read
    data = input().split()
    
    index = 0
    N = int(data[index])
    index += 1
    Q = int(data[index])
    index += 1
    
    A = list(map(int, data[index:index+N]))
    index += N
    
    cum_sum = []
    current_sum = 0
    
    for a in A:
        add = itertools.accumulate(range(1, a + 1))
        new_sums = [current_sum + x for x in add]
        cum_sum.extend(new_sums)
        current_sum = new_sums[-1] if new_sums else current_sum
    
    total = current_sum
    
    S = list(map(int, data[index:index+Q]))
    index += Q
    
    for s in S:
        if s > total:
            print(-1)
        else:
            pos = bisect.bisect_left(cum_sum, s)
            print(pos + 1)
    
if __name__ == "__main__":
    main()