#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> PP;
//#define MOD 1000000007
#define MOD 998244353
#define INF 2305843009213693951
//#define INF 810114514
#define PI 3.141592653589
#define setdouble setprecision
#define REP(i,n) for(ll i=0;i<(n);++i)
#define OREP(i,n) for(ll i=1;i<=(n);++i)
#define RREP(i,n) for(ll i=(n)-1;i>=0;--i)
#define ALL(v) (v).begin(), (v).end()
#define GOODBYE do { cout << "-1" << endl; return 0; } while (false)
#define MM <<" "<<
#define Endl endl
#define debug true
#define debug2 false

long long inverse(long long b,long long mod){
    /*
    Copyright (c) 2021 0214sh7
    https://github.com/0214sh7/library/
    */
    long long r=1,e=mod-2;
    while(e){
        if(e&1){
            r=(r*b)%mod;
        }
        b=(b*b)%mod;
        e >>=1;
    }
    return r;
}

int main(void){
    //cin.tie(nullptr);
    //ios::sync_with_stdio(false);

    ll N,M,P,Q;
    cin >> N >> M >> P >> Q;
    REP(i,Q){

        ll x,f;
        cin >> x >> f;

        ll y = (f*inverse(x%P,P))%P;
        //cout << y << endl;
        ll Ans = (M+P-y)/P;
        if(y ==0)Ans--;
        cout << Ans << endl;

    }

    return 0;
}