"""

https://yukicoder.me/problems/no/321

場合分けかなぁ

1,3

X.X.
...X
X...
.X.X

とりあえず必要条件を入れてみる

"""

import math

P,Q = map(int,input().split())
P = abs(P)
Q = abs(Q)

GPQ = math.gcd(P,Q)
GS  = math.gcd(abs(P-Q),abs(P+Q))

N = int(input())

ans = 0

for i in range(N):

    X,Y = map(int,input().split())
    X = abs(X)
    Y = abs(Y)

    flag = False

    if P == 0 and Q == 0:
        if X == Y == 0:
            flag = True
    else:
        if X % GPQ == 0 and Y % GPQ == 0 and (X+Y) % GS == 0 and abs(X-Y) % GS == 0:
            flag = True

    if flag:
        ans += 1

print (ans)