#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
#define ll long long
/*
hi, I'm rintaro.
AC is right
AC count is my life
But don't solve too many easy plobems!
*/
#define g(n,m) get<n>(m)
#define fof(i,o,n) for (ll i = o; i < (ll)n; i++)
#define fof_(dontuseit,a) for(auto &dontuseit : a)
#define vcin(a) fof_(i,a) cin>>i
#define all(o) o.begin(),o.end()
#define double long double
#define pii pair<ll,ll>
#define vec vector
#define vi vec<ll>
#define vs vec<string>
#define vc vec<char>
#define vvi vec<vi>
#define vpii vec<pii>
#define igpqueue priority_queue<ll,vi,greater<ll>>
#define re return
#define r0 re 0
#define ln(n) cout << n << endl
#define fix(n) << fixed << setprecision(n)
#define out_(n) << n << " "
#define Out cout
#define out(n) << n
#define End << endl
#define imap map<ll,ll>
#define smap map<string,ll>
#define gmap map<ll,vector<ll>>
#define m9 998244353
#define m7 1000000007
#define lny ln("Yes")
#define lnn ln("No")
long long modinv(long long a, long long m) {
    long long b = m, u = 1, v = 0;
    while (b) {
        long long t = a / b;
        a -= t * b; swap(a, b);
        u -= t * v; swap(u, v);
    }
    u %= m; 
    if (u < 0) u += m;
    return u;
}
int main() {
  ll N, M, P, Q;
  cin >> N >> M >> P >> Q;
  fof(i,0,Q) {
    ll a,f;
    cin>>a>>f;
    if(M%P>=(f*modinv(a,P)%P+(f*modinv(a,P)%P==0?P:0))) ln(M/P+1);
    else ln(M/P);
  }
}