#include<bits/stdc++.h>
#define inf 0x3f3f3f3f3f3f3f3fll
#define debug(x) cerr<<#x<<"="<<x<<endl
using namespace std;
using ll=long long;
using ld=long double;
using pli=pair<ll,int>;
using pi=pair<int,int>;
template<typename A>
using vc=vector<A>;
inline int read()
{
    int s=0,w=1;char ch;
    while((ch=getchar())>'9'||ch<'0') if(ch=='-') w=-1;
    while(ch>='0'&&ch<='9') s=s*10+ch-'0',ch=getchar();
    return s*w;
}
inline ll lread()
{
    ll s=0,w=1;char ch;
    while((ch=getchar())>'9'||ch<'0') if(ch=='-') w=-1;
    while(ch>='0'&&ch<='9') s=s*10+ch-'0',ch=getchar();
    return s*w;
}
ld dp[505][505];
ld fp[505][505];
int a[505];
int n,x,y;
int main()
{
    n=read(),x=read(),y=read();
    for(int i=1;i<=n;i++) a[i]=read();

    dp[0][0]=1;
    for(int i=1;i<=n;i++)
    {
        for(int j=n-1;j>=0;j--) for(int k=x-a[i];k>=0;k--) dp[j+1][k+a[i]]+=dp[j][k]*(j+1)/(n-j);
        // printf("i=%d : \n",i);
        // for(int j=0;j<=n;j++) for(int k=0;k<=x;k++) if(abs(dp[j][k])>1e-6)
        //     printf("%d %d : %Lf\n",j,k,dp[j][k]);
    }

    ld ans=0;
    for(int i=1;i<=n;i++)
    {
        memcpy(fp,dp,sizeof(fp));
        for(int j=0;j<n;j++) for(int k=0;k<=x;k++)
        {
            ld &val=fp[j][k];
            if(j<n&&j+a[i]<=x) fp[j+1][k+a[i]]-=val*(j+1)/(n-j);
            if(k<=x&&k+a[i]<=y&&k+a[i]>x)
            {
                ans+=fp[j][k]/(n-j);
                // if(abs(fp[j][k])>1e-6) printf("i=%d j=%d k=%d : %Lf\n",i,j,k,fp[j][k]/(n-j));
            }
        }
    }
    printf("%.10Lf\n",ans);
    return 0;
}