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)
biwgbSA9IG1hcChpbnQsIGlucHV0KCkuc3BsaXQoKSkKYT1saXN0KG1hcChpbnQsIGlucHV0KCkuc3BsaXQoKSkpCmI9bGlzdChtYXAoaW50LCBpbnB1dCgpLnNwbGl0KCkpKQpoYT1zdW0oYSkKaGI9c3VtKGIpCmlsZT0wCmlhID0gbi0xCmliID0gbS0xCndoaWxlKGhhIT1oYik6CiAgICBpbGUrPTEKICAgIGlmIGhhPmhiOgogICAgICAgIGhhIC09IGFbaWFdCiAgICAgICAgaWEgLT0gMQogICAgZWxzZToKICAgICAgICBoYiAtPSBiW2liXQogICAgICAgIGliIC09IDEKcHJpbnQgKGlsZSkK