#include <iostream>
#include <algorithm>
#include <string>
#include <utility>
#include <map>
#include <cmath>

#define MAX 100000
using namespace std;
typedef long long ll;
typedef pair<ll, ll> lp;


lp f(ll p, ll q){
	if(p > q) { // maybe needless
		swap(p,q);
	}
	if(p != 0){
		// p <= q
		// get min(|2xp-q|)
		ll tmp = p*2;
		ll x = p/tmp; // <=> 2xp-q == 0
		ll ans = min((ll)abs(x*tmp-q),(ll)abs((x+1)*tmp-q)); // min is x or x+1
		lp result;
		if(ans <= p){
			result.first = ans;
			result.second = p;
		}
		else {
			result.first = p;
			result.second = q;
		}
		return result;
	}
	else{
		lp result;
		result.first = p;
		result.second = q;
		return result;
	}
}

int main(){
	ll p,q;
	cin >> p >> q;
	if(p > q) { // always p<=q
		swap(p,q);
	}
	int n;
	cin >> n;
	lp* children = new lp[n];
	for(int i=0; i<n; i++){
		lp pos;
		ll tmp;
		cin >> tmp;
		pos.first = (ll)abs(tmp);
		cin >> tmp;
		pos.second = (ll)abs(tmp);
		children[i] = pos;
	}
	lp pos;
	pos.first = p;
	pos.second = q;
	while(true){
		pos = f(pos.first, pos.second);
		if(pos.first <= 0 ||  pos.first == pos.second){
			break;
		}
	}

	int result = 0;
	if(pos.first == 0 && pos.second == 0){
		for(int i=0; i<n; i++){
			if(children[i].first == 0 && children[i].second == 0){
				result++;
			}
		}
	}
	else if(pos.first == 0){
		for(int i=0; i<n; i++){
			if(children[i].first % pos.second == 0 && children[i].second % pos.second == 0){
				result++;
			}
		}
	}
	else { // pos.first == pos.second
		for(int i=0; i<n; i++){
			if((children[i].first + children[i].second)%(pos.first*2) == 0){
				result++;
			}
		}
	}
	cout << result << endl;
	return 0;
}