#! ruby
# yukicoder My Practice
# author: Leonardone @ NEETSDKASU

def gs(); gets.chomp; end
def gi(); gets.to_i; end
def gss(); gets.chomp.split; end
def gis(); gss.map(&:to_i); end

P, Q = gis
N = gi

d = P == Q ? P : (P - Q).abs

c = 0

N.times do
    x, y = gis.map(&:abs)
    c += 1 if x % d == 0 && y % d == 0
end

p c