# coding: utf-8
# Your code here!

x = list(map(int, input().split()))
num = int(input())
lst = []
for ls in range(num):
    lst.append(list(map (int ,input().split())))
ans = 0
print(lst)
for ele in lst:
    asm = 0
    A = abs(x[0] - x[1])
    B = abs(ele[0] - ele[1])
    if B == 0:
        continue
    elif B % A == 0:
        ans = ans + 1
    
print(ans)