#include <bits/stdc++.h>
using namespace std;
using ll= long long;
using ull=unsigned long long;
using ldo =long double;
#define rep(i,n,k) for(ll i = k; i < (ll)(n); i++)
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
const ll INF = 1e18;
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;

int main() {
  ll N,M,P,Q,x,f,Y,now,ans;
  cin>>N>>M>>P>>Q;
  rep(i,Q,0){
    cin>>x>>f;
    now=f;
    ans=0;
    while(now/x<=M){
      if(now%x==0){
        ans=(M-(now/x))/P+1;
        break;
      }
      now+=P;
    }
    cout<<ans<<endl;
  }
}