#include <bits/stdc++.h>
#define INIT std::ios::sync_with_stdio(false);std::cin.tie(0);
#define VAR(type, a) type a;std::cin>>a;
// VAR(int, x);
#define OUT(d) std::cout<<(d);
#define SP std::cout<<" ";
#define TAB std::cout<<"\t";
#define BR std::cout<<"\n";
#define ENDL std::cout<<std::endl;
#define FLUSH std::cout<<std::flush;
#define VEC(type, c, n) std::vector<type> c(n);for(auto& i:c)std::cin>>i;
#define MAT(type, c, m, n) std::vector<std::vector<type>> c(m, std::vector<type>(n));for(auto& r:c)for(auto& i:r)std::cin>>i;
#define ALL(a) (a).begin(),(a).end()
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define POS std::pair<int, int>
#define IN(a0, y, a1, b0, x, b1) (a0<=y && y<a1 && b0<=x && x<b1)
#define SHOWVECTOR2(v) {std::cout << #v << "\t:\n";for(auto i : v){for(auto j : i){std::cout << j << " ";}std::cout << "\n";}}

#define int ll
using ll = long long;

int GCD(int a, int b){
    return b!=0?GCD(b, a%b):a;
}

signed main(){
    INIT;
    VAR(ll, p)VAR(ll, q)VAR(ll, n);
    std::vector<ll> x(n), y(n);
    REP(i, n){
        std::cin >> x[i] >> y[i];
        x[i] = std::fabs(x[i]);
        y[i] = std::fabs(y[i]);
    }
    int cnt = 0;
    if(p==0 && q==0){
        REP(i, n)if(x[i]==0 && y[i]==0) ++cnt;
    }
    else if(p==0 || q==0){
        int t = std::max(p, q);
        REP(i, n)if(x[i]%t==0 && y[i]%t==0) ++cnt;
    }
    else{
        ll t = GCD(p, q);
        if(p%2==q%2){
            REP(i, n)if(x[i]%t==0 && y[i]%t==0 /*&& (x[i]+y[i])%(t*2)==0*/) ++cnt;
        }
        else{
            REP(i, n)if(x[i]%t==0 && y[i]%t==0) ++cnt;
        }
    }
    OUT(cnt)BR;
    return 0;
}