#include <bits/stdc++.h>
using namespace std;
struct p {
  double x;
  double y;
};
bool cmp(p a, p b) {
  if (a.y < b.y) return true;
  if (a.y == b.y && a.x > b.x) return true;
  return false;
}
int main() {
  p a[10000];
  double w, u, v;
  int n;
  cin >> n >> w >> v >> u;
  cout << fixed << setprecision(10);
  for (int i = 0; i < n; i++) cin >> a[i].x >> a[i].y;
  bool f = true;
  for (int i = 0; i < n; i++)
    if (a[i].x * u < a[i].y * v) {
      f = false;
      break;
    }
  if (f == true) {
    cout << w / u << endl;
    return 0;
  }
  double res = w / u;
  for (int i = 0; i < n; i++) {
    if (a[i].x * u > a[i].y * v) res = max(a[i].x / v + (w - a[i].y) / u, res);
  }
  cout << res << endl;
}
