#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
const int N = 1e4L + 11;
ll x[N], y[N];
int main() {
  ios ::sync_with_stdio(0);
  cout << fixed << setprecision(9);
  int n;
  ll w, v, u;
  cin >> n >> w >> v >> u;
  for (int i = 0; i < n; i++) cin >> x[i] >> y[i];
  bool l = 0, r = 0;
  for (int i = 0; i < n; i++) {
    ll t = v * y[i] - u * x[i];
    if (t > 0) l = 1;
    if (t < 0) r = 1;
  }
  if (l && r) {
    ld t = 0;
    for (int i = 0; i < n; i++) t = max(t, (x[i] - ld(y[i]) / u * v) / v);
    cout << t + ld(w) / u << '\n';
  } else
    cout << ld(w) / u << '\n';
  return 0;
}
