public static void main ( String [ ] args ) {
  Scanner scanner = new Scanner ( System . in ) ;
  int length = scanner . nextInt ( ) ;
  int city1 = scanner . nextInt ( ) ;
  int city2 = scanner . nextInt ( ) ;
  int [ ] people = new int [ length ] ;
  for ( int i = 0 ;
  i < length ;
  i ++ ) people [ i ] = scanner . nextInt ( ) ;
  Arrays . sort ( people ) ;
  long sum1 = 0 ;
  long sum2 = 0 ;
  for ( int i = length - 1 ;
  i >= length - Math . min ( city1 , city2 ) ;
  i -- ) sum1 += people [ i ] ;
  for ( int i = length - Math . min ( city1 , city2 ) - 1 ;
  i >= length - city1 - city2 ;
  i -- ) sum2 += people [ i ] ;
  double answer = 1d * sum2 / Math . max ( city1 , city2 ) + 1d * sum1 / Math . min ( city1 , city2 ) ;
  System . out . print ( answer ) ;
}

public static void main ( String [ ] args ) { Scanner scanner = new Scanner ( System . in ) ; int length = scanner . nextInt ( ) ; int city1 = scanner . nextInt ( ) ; int city2 = scanner . nextInt ( ) ; int [ ] people = new int [ length ] ; for ( int i = 0 ; i < length ; i ++ ) people [ i ] = scanner . nextInt ( ) ; Arrays . sort ( people ) ; long sum1 = 0 ; long sum2 = 0 ; for ( int i = length - 1 ; i >= length - Math . min ( city1 , city2 ) ; i -- ) sum1 += people [ i ] ; for ( int i = length - Math . min ( city1 , city2 ) - 1 ; i >= length - city1 - city2 ; i -- ) sum2 += people [ i ] ; double answer = 1d * sum2 / Math . max ( city1 , city2 ) + 1d * sum1 / Math . min ( city1 , city2 ) ; System . out . print ( answer ) ; }
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