#include <bits/stdc++.h>
using namespace std;
bool flag = true;
int n, w, v, u;
double lt;
void first(int x, int y);
void second(int x, int y);
int main() {
  int x, y;
  cin >> n >> w >> v >> u;
  for (int i = 1; i <= n; i++) {
    cin >> x >> y;
    first(x, y);
    second(x, y);
  }
  double d = w;
  double nt = d / u;
  if (flag)
    cout << setprecision(12) << nt;
  else
    cout << setprecision(10) << lt + nt;
  return 0;
}
void first(int x, int y) {
  double x1 = x, y1 = y;
  double nt = x1 / v;
  double ut = y1 / u;
  if (nt < ut) flag = false;
}
void second(int x, int y) {
  double x1 = x, y1 = y;
  double nt = x1 / v;
  double ut = y1 / u;
  if (nt - ut > lt) lt = nt - ut;
}
