#include <bits/stdc++.h>
#define REP(i, a, n) for(ll i = ((ll) a); i < ((ll) n); i++)
using namespace std;
typedef long long ll;

ll P, Q, N, X[100000], Y[100000];
ll g;

ll gcd(ll a, ll b) { return b != 0 ? gcd(b, a % b) : a; }

bool ok(ll x, ll y) {
  if(P == 0 && Q == 0) return x == 0 && y == 0;
  if(P == 0 || Q == 0) return x % max(P, Q) == 0 && y % max(P, Q) == 0;
  if(P % 2 == Q % 2) return x % g == 0 && y % g == 0 && (x / g + y / g) % 2 == 0;
  return x % g == 0 && y % g == 0;
}

int main(void) {
  cin >> P >> Q >> N;
  REP(i, 0, N) cin >> X[i] >> Y[i];

  if(P != 0 && Q != 0) {
    g = gcd(P, Q);
    P = P / g;
    Q = Q / g;
  }

  // cout << P << " " << Q << endl;

  ll ans = 0;
  REP(i, 0, N) if(ok(X[i], Y[i])) ans++;
  cout << ans << endl;
}