import sys
import numpy as np
from math import gcd

input = sys.stdin.buffer.readline

P, Q = map(int, input().split())
N = int(input())
XY = np.array([tuple(map(int, input().split())) for _ in range(N)])
if (P, Q) == (0, 0):
    print(np.count_nonzero(np.all(XY == 0, axis=1)))
    exit()

g = gcd(P, Q)
P, Q = P // g, Q // g
XY = XY[np.all(XY % g == 0, axis=1)] // g
N = len(XY)

if (P + Q) % 2:
    print(N)
else:
    print(np.count_nonzero(np.sum(XY, axis=1) % 2 == 0))