#include <bits/stdc++.h>
const int INF = 0x3f3f3f3f;
const double PI = acos(-1.0);
const int MAX = 1e5 + 10;
const long long mod = 1e9 + 7;
using namespace std;
int main() {
  double n, w, v, u;
  while (scanf("%lf%lf%lf%lf", &n, &w, &v, &u) != EOF) {
    double x, y;
    double minn = INF * 1.0, maxn = -INF * 1.0;
    for (int i = 0; i < n; i++) {
      scanf("%lf%lf", &x, &y);
      minn = min(minn, x - y * v * 1.0 / u);
      maxn = max(maxn, x - y * v * 1.0 / u);
    }
    if (minn >= -1e-8)
      printf("%.10lf\n", w * 1.0 / u);
    else if (maxn >= -1e-8)
      printf("%.10lf\n", maxn * 1.0 / v + w * 1.0 / u);
    else
      printf("%.10lf\n", w * 1.0 / u);
  }
  return 0;
}
