from math import gcd

p, q = map(int, input().split())
n = int(input())
P = [list(map(int, input().split())) for _ in range(n)]

ans = 0
if p == q == 0:
    for i in range(n):
        x, y = P[i]
        if x == y == 0:
            ans += 1
else:
    g = gcd(p, q)
    p //= g
    q //= g
    if (p + q) % 2 == 0:
        bi = True
    else:
        bi = False
    for i in range(n):
        x, y = P[i]
        if x % g != 0 or y % g != 0:
            continue
        x //= g
        y //= g
        if not bi or (x + y) % 2 == 0:
            ans += 1
print(ans)