#!/bin/python3

import sys

from functools import reduce

def multiples_of_a_divisors_of_b(lcm, gcd):

result = []

multiplyer = 1

while (lcm * multiplyer <= gcd):

if (gcd % (lcm * multiplyer) == 0):

result.append(lcm * multiplyer)

multiplyer += 1

return result

# Import gcd and lcm from https://gist.github.com/endolith/114336

def gcd(*numbers):

"""Return the greatest common divisor of the given integers"""

from fractions import gcd

return reduce(gcd, numbers)

def lcm(*numbers):

"""Return lowest common multiple."""

def lcm(a, b):

return (a * b) // gcd(a, b)

return reduce(lcm, numbers, 1)

if __name__ == "__main__":

n, m = map(int, input().strip().split(' '))

a = list(map(int, input().strip().split(' ')))

b = list(map(int, input().strip().split(' ')))

print(len(multiples_of_a_divisors_of_b(lcm(*a), gcd(*b))))