#include <bits/stdc++.h>
using namespace std;
const long long int MOD = 1e9 + 7;
bool IsPowerOfTwo(long long int x) { return (x != 0) && ((x & (x - 1)) == 0); }
long long int poer(long long int a, long long int b) {
  long long int rs = 1;
  while (b > 0) {
    if (b & 1) rs *= a;
    a *= a;
    b /= 2;
  }
  return rs;
}
long long int mod_poer(long long int a, long long int b, long long int mo) {
  long long int rs = 1;
  while (b > 0) {
    if (b & 1) rs = (rs * a) % mo;
    a = (a * a) % mo;
    b /= 2;
  }
  return rs % mo;
}
long long int d, x, y;
void ext_euclid(long long int a, long long int b) {
  if (b == 0) {
    d = a;
    x = 1;
    y = 0;
  } else {
    ext_euclid(b, a % b);
    long long int temp = x;
    x = y;
    y = temp - (a / b) * y;
  }
}
long long int mod_inverse1(long long int a, long long int m) {
  ext_euclid(a, m);
  return (x % m + m) % m;
}
long long int mod_inverse2(long long int a, long long int m) {
  return mod_poer(a, m - 2, m);
}
long long int gcd(long long int a, long long int b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
long long int fact[200005];
void fac() {
  fact[1] = fact[0] = 1;
  for (long long int i = 2; i <= 200005; ++i) {
    fact[i] = ((fact[i - 1] % MOD) * i) % MOD;
  }
}
long long int combi(long long int a, long long int b) {
  if (b > a) return 0;
  if (b == a)
    return 1;
  else {
    long long int x = mod_poer(fact[b], MOD - 2, MOD) % MOD;
    long long int y = mod_poer(fact[a - b], MOD - 2, MOD) % MOD;
    return ((((fact[a]) * x) % MOD) * y) % MOD;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n, flg = 0;
  double w, v, u;
  cin >> n >> w >> v >> u;
  vector<pair<long long int, long long int>> vec;
  for (long long int i = 0; i < n; ++i) {
    long long int xi, yi;
    cin >> xi >> yi;
    vec.push_back({yi, xi});
    if ((double)xi / (double)v < (double)yi / (double)u) flg++;
  }
  if (!flg) {
    cout << fixed << setprecision(10) << (double)w / (double)u << endl;
    return 0;
  }
  sort(vec.begin(), vec.end());
  double xi = 0, yi = 0, pre = 0, tim = 0;
  for (long long int i = 0; i < n; ++i) {
    if (vec[i].second < xi) continue;
    xi = vec[i].second;
    tim = max(1.0 * xi / v, tim + (1.0 * ((vec[i].first - yi) / u)));
    yi = vec[i].first;
  }
  tim += 1.0 * (w - yi) / u;
  cout << fixed << setprecision(10) << tim << endl;
  return 0;
}
