module main;
// http://rsujskf.s602.xrea.com/?yukicoder_321 より
// 2次元グリッド
import std;

void main()
{
	// 入力
	int P, Q;
	readln.chomp.formattedRead("%d %d", P, Q);
	int N = readln.chomp.to!int;
	alias T = Tuple!(int, "x", int, "y");
	auto pts = new T[](N);
	foreach (ref p; pts)
		readln.chomp.formattedRead("%d %d", p.x, p.y);
	// 答えの計算と出力
	if (P == 0) {
		if (Q == 0) {
			writeln(pts.count(T(0, 0)));
			return;
		}
		writeln(pts.count!(a => a.x % Q == 0 && a.y % Q == 0));
		return;
	}
	if (Q == 0) {
		writeln(pts.count!(a => a.x % P == 0 && a.y % P == 0));
		return;
	}
	int g = gcd(P, Q);
	P /= g, Q /= g;
	int ans = 0;
	foreach (p; pts) {
		if (p.x % g || p.y % g)
			continue;
		p.x /= g, p.y /= g;
		if ((P + Q) % 2 == 0 && (p.x + p.y) % 2 != 0)
			continue;
		ans++;
	}
	writeln(ans);
}