public static void main ( String [ ] args ) {
  Scanner fs = new Scanner ( System . in ) ;
  int n = fs . nextInt ( ) , a = fs . nextInt ( ) , b = fs . nextInt ( ) ;
  int orig = a + b ;
  char [ ] line = fs . next ( ) . toCharArray ( ) ;
  ArrayList < Integer > sizes = new ArrayList < > ( ) ;
  int size = 0 ;
  for ( char c : line ) {
    if ( c == '*' ) {
      sizes . add ( size ) ;
      size = 0 ;
    }
    else {
      size ++ ;
    }
  }
  sizes . add ( size ) ;
  for ( int i : sizes ) {
    int big = ( i + 1 ) / 2 , small = i - big ;
    int bigger = Math . max ( a , b ) , smaller = Math . min ( a , b ) ;
    b = Math . max ( 0 , bigger - big ) ;
    a = Math . max ( 0 , smaller - small ) ;
  }
  System . out . println ( orig - a - b ) ;
}

public static void main ( String [ ] args ) { Scanner fs = new Scanner ( System . in ) ; int n = fs . nextInt ( ) , a = fs . nextInt ( ) , b = fs . nextInt ( ) ; int orig = a + b ; char [ ] line = fs . next ( ) . toCharArray ( ) ; ArrayList < Integer > sizes = new ArrayList < > ( ) ; int size = 0 ; for ( char c : line ) { if ( c == ' * ' ) { sizes . add ( size ) ; size = 0 ; } else { size ++ ; } } sizes . add ( size ) ; for ( int i : sizes ) { int big = ( i + 1 ) / 2 , small = i - big ; int bigger = Math . max ( a , b ) , smaller = Math . min ( a , b ) ; b = Math . max ( 0 , bigger - big ) ; a = Math . max ( 0 , smaller - small ) ; } System . out . println ( orig - a - b ) ; }
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