```
class Solution(object):
def fourSumCount(self, A, B, C, D):
"""
:type A: List[int]
:type B: List[int]
:type C: List[int]
:type D: List[int]
:rtype: int
"""
hashtable = {}
for a in A:
for b in B :
if a + b in hashtable :
hashtable[a+b] += 1
else :
hashtable[a+b] = 1
count = 0
for c in C :
for d in D :
if -c - d in hashtable :
count += hashtable[-c-d]
return count
```