#include <bits/stdc++.h>
using namespace std;
double w, v, u, xx[1000000], yy[1000000];
long long n, i, j;
double t, maxi, mini, lik;
int main() {
  cin >> n >> w >> v >> u;
  maxi = -10000000000;
  mini = 100000000000;
  for (i = 1; i <= n; i++) {
    cin >> xx[i] >> yy[i];
    t = (yy[i] / u);
    lik = xx[i] - (t * v);
    if (lik < mini) mini = lik;
    if (lik > maxi) maxi = lik;
  }
  if ((mini <= 0 && maxi <= 0) || (mini >= 0 && maxi >= 0))
    printf("%lf", w / u);
  else {
    lik = (maxi / v) + (w / u);
    printf("%lf", lik);
  }
  return 0;
}
