public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  String input = sc . nextLine ( ) ;
  int count = 0 ;
  String inputStr [ ] = new String [ input . length ( ) ] ;
  int currentIndex = 0 ;
  for ( int i = 0 ;
  i < input . length ( ) ;
  i ++ ) {
    inputStr [ currentIndex ] = input . substring ( i , i + 1 ) ;
    if ( currentIndex != 0 && ! inputStr [ currentIndex ] . equals ( inputStr [ currentIndex - 1 ] ) ) {
      currentIndex -- ;
      count += 2 ;
    }
    else {
      currentIndex ++ ;
    }
  }
  System . out . println ( count ) ;
  sc . close ( ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; String input = sc . nextLine ( ) ; int count = 0 ; String inputStr [ ] = new String [ input . length ( ) ] ; int currentIndex = 0 ; for ( int i = 0 ; i < input . length ( ) ; i ++ ) { inputStr [ currentIndex ] = input . substring ( i , i + 1 ) ; if ( currentIndex != 0 && ! inputStr [ currentIndex ] . equals ( inputStr [ currentIndex - 1 ] ) ) { currentIndex -- ; count += 2 ; } else { currentIndex ++ ; } } System . out . println ( count ) ; sc . close ( ) ; }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier))) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (type_identifier) arguments: (argument_list (field_access object: (identifier) field: (identifier)))))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) dimensions: (dimensions) value: (array_creation_expression type: (type_identifier) dimensions: (dimensions_expr (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) update: (update_expression (identifier)) body: (block (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (binary_expression left: (identifier) right: (decimal_integer_literal)))))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (unary_expression operand: (method_invocation object: (array_access array: (identifier) index: (identifier)) name: (identifier) arguments: (argument_list (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal)))))))) consequence: (block (expression_statement (update_expression (identifier))) (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal)))) alternative: (block (expression_statement (update_expression (identifier))))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier)))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))