#include <bits/stdc++.h>
using namespace std;
int n;
long long x[10002], y[10002], d[10002], w, u, v;
int main() {
  cin >> n >> w >> v >> u;
  for (int i = 1; i <= n; i++) {
    cin >> x[i] >> y[i];
    d[i] = y[i] * v - x[i] * u;
  }
  x[n + 1] = x[1];
  y[n + 1] = y[1];
  double ans = w * 1.0 / u;
  long long min = 0, max = 0, imin = 0, imax = 0;
  for (int i = 1; i <= n; i++) {
    if (d[i] > max || imax == 0) {
      max = d[i];
      imax = i;
    }
    if (d[i] < min || imin == 0) {
      min = d[i];
      imin = i;
    }
  }
  if (max > 0 && min < 0) ans += -min * 1.0 / u / v;
  cout << fixed << setprecision(10) << ans << endl;
  return 0;
}
