public static void main ( String [ ] args ) {
  BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ;
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  if ( n >= 1 && n <= 999 ) System . out . println ( "ABC" ) ;
  else if ( n > 999 ) System . out . println ( "ABD" ) ;
}

public static void main ( String [ ] args ) { BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ; Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; if ( n >= 1 && n <= 999 ) System . out . println ( " ABC " ) ; else if ( n > 999 ) System . out . println ( " ABD " ) ; }
(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 (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: (object_creation_expression type: (type_identifier) arguments: (argument_list (field_access object: (identifier) field: (identifier)))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (binary_expression left: (identifier) right: (decimal_integer_literal)))) consequence: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal)))) alternative: (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) consequence: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal))))))))