#include <bits/stdc++.h>
using namespace std;
const int N = 10010;
int n, w, v, u;
double ans, x[N], y[N];
int main() {
  int l;
  int i, j;
  scanf("%d%d%d%d", &n, &w, &v, &u);
  ans = 0;
  int f1 = 1, f2 = 1;
  ans = 0;
  for (i = 0; i < n; i++) {
    scanf("%lf%lf", x + i, y + i);
    if ((x[i] / v) > (y[i] / u)) {
      f1 = 0;
    }
    if ((x[i] / v) < (y[i] / u)) f2 = 0;
    ans = max(ans, x[i] / v + (double)(w - y[i]) / u);
  }
  if (f1 + f2 > 0) {
    double t = (double)w / u;
    printf("%.10lf", t);
  } else
    printf("%0.10lf", ans);
  return 0;
}
