3 2 7 2
1 5 1 2 3 2

2

from collections import deque
a=list(map(int,input().split()))
b=list(map(int,input().split()))
total=sum(a)+sum(b)
if total%2!=0: print(-1)
else:
    target=total//2
    qa=deque(a); qb=deque(b)
    sa=sum(a); sb=sum(b); count=0
    limit=(len(a)+len(b))*3
    while sa!=sb and count<=limit:
        if sa>target: v=qa.popleft(); sa-=v; qb.append(v); sb+=v
        else: v=qb.popleft(); sb-=v; qa.append(v); sa+=v
        count+=1
    print(count if sa==sb else -1)