#include "bits/stdc++.h"
using namespace std;
#ifdef _DEBUG
#include "dump.hpp"
#else
#define dump(...)
#endif

#define int long long
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(c) begin(c),end(c)
const int INF = sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = 1'000'000'007;
template<class T> bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, const T &b) { if (b < a) { a = b; return true; } return false; }

int gcd(int x, int y) { return y ? gcd(y, x % y) : x; }

signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int P, Q; cin >> P >> Q;
	int N; cin >> N;
	vector<int> X(N), Y(N); rep(i, 0, N) {
		cin >> X[i] >> Y[i];
	}
	if (P == 0 && Q == 0) {
		rep(i, 0, N) {
			if (X[i] == 0 && Y[i] == 0) {
				cout << 1 << endl;
				return 0;
			}
		}
		cout << 0 << endl;
	}
	else {
		int g = abs(P - Q) == 0 ? P + Q : gcd(P + Q, abs(P - Q));
		dump(g);
		int ans = 0;
		rep(i, 0, N) {
			if (X[i] % g == 0 && Y[i] % g == 0 && (X[i] + Y[i]) % g == 0) {
				ans++;
			}
		}
		cout << ans << endl;
	}
	return 0;
}