#include <bits/stdc++.h>

using namespace std;

int main()
{
    long long n, m;
    cin>>n>>m;
    long long sx, sy;
    cin>>sx>>sy;
    long long k;
    cin>>k;
    vector<pair<long long, long long>> v;
    for(long long i = 0; i< k; i++)
    {
        long long x, y;
        cin>>x>>y;
        v.push_back(make_pair(x, y));
    }
    long long nr_steps = 0;
    for(long long i = 0; i< k; i++)
    {
        /*while(sx+v[i].first>=1 && sx+v[i].first<=n && sy+v[i].second>=1 && sy+v[i].second<=m)
        {
            nr_steps++;
            sx+=v[i].first;
            sy+=v[i].second;
        }*/
        long long v1, v2;
        if(v[i].first>0)
        {
            v1 = (n-sx)/v[i].first;
        }
        else if(v[i].first)
        {

            v1 = (sx - 1)/(-v[i].first);
        }
        else{
            v1 = n +1;
        }
        if(v[i].second>0)
        {
            v2 = (m-sy)/v[i].second;
        }
        else if(v[i].second)
        {

            v2 = (sy - 1)/(-v[i].second);
        }
        else{
            v2 = m +1;
        }
        sx += min(v1, v2)*v[i].first;
        sy += min(v1, v2)*v[i].second;
        nr_steps += min(v1, v2);
    }
    cout<<nr_steps;
    return 0;
}