#include <bits/stdc++.h>
using namespace std;
const long double EPS = 1e-8;
const int INF = (int)(1e8);
const long long mod = (int)(1e+9 + 7);
const int N = (int)(1e3);
int days_month[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int main() {
  cout.precision(18);
  long double n, m, w, vx, vy;
  cin >> n >> w >> vx >> vy;
  long double x, y;
  long double l = INF, r = 0;
  for (int i = 0; i < n; i++) {
    cin >> x >> y;
    long double t = y / vy;
    l = min(l, x - vx * t);
    r = max(r, x - vx * t);
  }
  if (!(l < 0 && 0 < r)) return cout << w / vy, 0;
  ;
  cout << r / vx + w / vy;
  return 0;
}
