/* Author haleyk10198 */
/* 作者: haleyk10198 */
#include <iostream>
#include <fstream>
#include <sstream>
#include <cstdlib>
#include <cstdio>
#include <vector>
#include <map>
#include <queue>
#include <cmath>
#include <algorithm>
#include <cstring>
#include <iomanip>
#include <ctime>
#include <string>
#include <set>
#include <stack>
#define MOD 1000000007
#define INF 2147483647
#define PI 3.1415926535897932384626433
#define ll long long
#define pii pair<int,int>
#define mp(x,y) make_pair((x),(y))
using namespace std;
pii a[10010];
struct Custom{
bool operator()(pii a,pii b){
return a.second<b.second||(a.second==b.second&&a.first<b.first);
}
};
int main(){
//freopen("input.txt","r",stdin);
//freopen("output.txt","w",stdout);
ios_base::sync_with_stdio(false);
int n;
double w,v,u;
bool f=true;
cin>>n>>w>>v>>u;
for(int i=0;i<n;i++){
cin>>a[i].first>>a[i].second;
if(1.0*a[i].first/v<1.0*a[i].second/u)
f=false;
}
if(f)
cout<<fixed<<setprecision(12)<<1.0*w/u;
else{
sort(a,a+n,Custom());
double x,y,t;
x=y=t=0;
for(int i=0;i<n;i++){
if(a[i].first<x)
continue;
x=a[i].first;
t=max(1.0*x/v,t+1.0*(a[i].second-y)/u);
y=a[i].second;
}
t+=1.0*(w-y)/u;
cout<<fixed<<setprecision(12)<<t<<endl;
}
return 0;
}
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