#include<bits/stdc++.h>

using namespace std;

const int N = 5005;

long long n, j, b, c, vv = 1e18, ss = 1e18, ans, a, s[N], v[N];

int main(){
  cin >> n >> a >> b >> c;
  for(long long i = 1; i <= n; ++i){
    cin >> s[i] >>  v[i];
    vv = min(vv, v[i]);
    ss = min(ss, s[i]);
  }
  for(long long i = 1; i <= n; ++i){
    if(a * (s[i] - ss) + b * (v[i] - vv) <= c){
      ans++;
    }
  }
  cout << ans;
  return 0;
}