> #include<cstdio>
> #include<cstdlib>
> #include<string>
> #include<cmath>
> #include<iostream>
> #include<fstream>
> #include<iomanip>
> #include<vector>
> #include<algorithm>
> #include<map>
> 
> using namespace std;
> int  arr[5000005];
> struct greaterthan
> {	
> 	bool operator()(const int& _Left, const int& _Right) const
> 	{	
> 		return (_Left > _Right);
> 	}
> };
> 
> struct lessthan
> {	
> 	bool operator()(const int& _Left, const int& _Right) const
> 	{	
> 		return (_Left < _Right);
> 	}
> };
> 
> int main()
> {
> 	int num, low, high, avr, n, ii;
> 	__int64 total;
> 	while(true)
> 	{
> 		scanf("%d%d%d",&low,&high, &num);
> 		if((low == 0) && (high == 0) && (num == 0)) break;
> 		for(ii = 0; ii < num; ii++)
> 		{
> 			scanf("%d",arr + ii);
> 		}
> 		nth_element(arr + 0  , arr + low,  arr + num, greaterthan());
> 		nth_element(arr + low, arr + high, arr + num, lessthan());
> 		for(ii = low + high, total = 0L;ii < num; ii++)
> 		{
> 			total += arr[ii];
> 		}
> 		printf("%.6lf\n",(double)(total)/(double)(num - low - high));
> 	}
> 	return 0;
> }