#include<cstdio>#include<cstring>#include<algorithm>using namespace std;double dp[110],cost[10010];int dis[110],INF=1e9+7;int main(){ int n,m,i,j,k,r; double d,b,v,e,f,ret; while(~scanf("%d",&n) && n) { for(i=1;i<=n;i++)scanf("%d",&dis[i]); scanf("%lf%d%lf%lf%lf",&d,&r,&v,&e,&f); for(i=0;i<dis[n];i++) { if(i<r) ret=1.0/(v-f*(r-i)); else ret=1.0/(v-e*(i-r)); if(i==0) cost[i]=ret; else cost[i]=cost[i-1]+ret; } for(i=1;i<=n;i++)dp[i]=INF; dp[0]=0; for(i=0;i<n;i++) { if(i==0) ret=0; else ret=d; for(j=i+1;j<=n;j++) dp[j]=min(dp[j],dp[i]+cost[dis[j]-dis[i]-1]+ret); } printf("%.4fn",dp[n]); }}
