from collections import deque
def solution(queue1, queue2):
    goal=(sum(queue1)+sum(queue2))/2
    queue1=deque(queue1)
    queue2=deque(queue2)
    answer = 0
    left_sum=sum(queue1)
    while queue1 and queue2:
        if left_sum>goal:
            a=queue1.popleft()
            queue2.append(a)
            left_sum-=a
            answer+=1
        elif left_sum<goal:
            a=queue2.popleft()
            queue1.append(a)
            left_sum+=a
            answer+=1
        else:
            return answer
    else:
        return -1