//poj2833优先队列。数据量太大，而且没有必要全部排序。
//优先队列
//*
#include<iterator>
#include <stdio.h>
#include <queue>
#include<algorithm>
#include<iterator>
using namespace std;
int main(){
long n1,n2;
long n,t;
priority_queue<long> minQ;
priority_queue<long,vector<long>,greater<long> > maxQ;
while(scanf("%ld%ld%ld",&n1,&n2,&n)){
if(n==0&&n1==0&&n2==0) break;
long long sum=0;
for(int i=0;i<n;i++){
scanf("%ld",&t);
sum+=t;
minQ.push(t);
maxQ.push(t);
if(minQ.size()>n2) minQ.pop();
if(maxQ.size()>n1) maxQ.pop();
}
while(!minQ.empty()) {sum-=minQ.top();minQ.pop();}
while(!maxQ.empty()) {sum-=maxQ.top();maxQ.pop();}
printf("%.6f\n",1.0*(sum)/(n-n1-n2));
}
return 0;
}
//*/
