#include <bits/stdc++.h>
const double dou = 1e-10;
const double inf = 0x3f3f3f3f;
using namespace std;
double n, l, v, u;
double x, y;
double maxn = -inf * 1.0;
double minn = inf * 1.0;
int main() {
  scanf("%lf%lf%lf%lf", &n, &l, &v, &u);
  for (int i = 1; i <= n; i++) {
    scanf("%lf%lf", &x, &y);
    minn = min(minn, x - (y * v / u));
    maxn = max(maxn, x - (y * v / u));
  }
  if (minn >= -dou)
    printf("%.10lf", l / u);
  else if (maxn >= -dou)
    printf("%.10lf", maxn / v + l / u);
  else
    printf("%.10lf", l / u);
  return 0;
}
