#include<bits/stdc++.h>
#define REP(x,y,z) for(int x=y;x<=z;x++)
#define FORD(x,y,z) for(int x=y;x>=z;x--)
#define MSET(x,y) memset(x,y,sizeof(x))
#define FOR(x,y) for(__typeof(y.begin()) x=y.begin();x!=y.end();x++)
#define F first
#define S second
#define MP make_pair
#define PB push_back
#define SZ size()
#define M 
void RI(){}
template<typename... T>
void RI( int& head, T&... tail ) {
    scanf("%d",&head);
    RI(tail...);
}
using namespace std;
typedef long long LL;
int main()
{
	int p,q,gcd;
	int n,x,y;
	int ans;
	while(~scanf("%d %d",&p,&q))
	{
		ans=0;
		gcd = __gcd(p,q);
		RI(n);
		while(n--)
		{
			RI(x,y);
			x = abs(x);
			y = abs(y);
			if(x%gcd==0 && y%gcd==0)
			{
				int diff = abs(p-q);
				if(diff>0 && abs(x-y)%diff==0) ans++;
			}
		}
		printf("%d\n",ans);
	}
	return 0;
}