n, m = map(int, input().split())
a=list(map(int, input().split()))
b=list(map(int, input().split()))
ha=sum(a)
hb=sum(b)
ile=0
ia = n-1
ib = m-1
while(ha!=hb):
    ile+=1
    if ha>hb:
        ha -= a[ia]
        ia -= 1
    else:
        hb -= b[ib]
        ib -= 1
print (ile)