#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi=acos(-1.0),eps=1e-8;
void File()
{freopen("D:\\in.txt","r",stdin);freopen("D:\\out.txt","w",stdout);
}const int INF=2000000000;
const int maxn=10010;
int n,w,v,u,len1,len2;
struct X { int x,y; }p[maxn],L[maxn],R[maxn];int main()
{scanf("%d%d%d%d",&n,&w,&v,&u);for(int i=1;i<=n;i++) scanf("%d%d",&p[i].x,&p[i].y);int ymin=INF,ymax=-INF,f,p1,p2; bool flag;for(int i=1;i<=n;i++) ymin=min(ymin,p[i].y), ymax=max(ymax,p[i].y);f=INF; for(int i=1;i<=n;i++) if(p[i].y==ymin&&p[i].x<f) f=p[i].x,p1=i;f=INF; for(int i=1;i<=n;i++) if(p[i].y==ymax&&p[i].x<f) f=p[i].x,p2=i;flag=0; for(int i=p1;i>=1;i--) { L[len1++]=p[i]; if(i==p2) { flag=1; break; } }if(flag==0) for(int i=n;i>=p2;i--) L[len1++]=p[i];f=-INF; for(int i=1;i<=n;i++) if(p[i].y==ymin&&p[i].x>f) f=p[i].x,p2=i;f=-INF; for(int i=1;i<=n;i++) if(p[i].y==ymax&&p[i].x>f) f=p[i].x,p1=i;flag=0; for(int i=p1;i>=1;i--) { R[len2++]=p[i]; if(i==p2) { flag=1; break; } }if(flag==0) for(int i=n;i>=p2;i--) R[len2++]=p[i];for(int i=0;i<len2/2;i++) swap(R[i],R[len2-i-1]);bool fail=0; for(int i=0;i<len1;i++) if((LL)L[i].y*(LL)v>(LL)L[i].x*(LL)u) { fail=1; break; }int xmax=-INF; for(int i=1;i<=n;i++) xmax=max(xmax,p[i].x);if(xmax<=0) fail=0;if(fail==0) printf("%.6lf\n",1.0*w/u);else{double ans=0; int pre=0;for(int i=0;i<len2;i++){ans=ans+1.0*(R[i].y-pre)/u; pre=R[i].y;ans=max(ans,1.0*R[i].x/v);}ans=ans+1.0*(w-pre)/u;printf("%.6lf\n",ans);}return 0;
}