public static void main ( String [ ] args ) throws Exception {
  Scanner sc = new Scanner ( System . in ) ;
  String b = sc . nextLine ( ) ;
  String str = "" ;
  switch ( b ) {
    case "A" : str = "T" ;
    break ;
    case "T" : str = "A" ;
    break ;
    case "C" : str = "G" ;
    break ;
    case "G" : str = "C" ;
    break ;
    default : break ;
  }
  System . out . println ( str ) ;
}

public static void main ( String [ ] args ) throws Exception { Scanner sc = new Scanner ( System . in ) ; String b = sc . nextLine ( ) ; String str = " " ; switch ( b ) { case " A " : str = " T " ; break ; case " T " : str = " A " ; break ; case " C " : str = " G " ; break ; case " G " : str = " C " ; break ; default : break ; } System . out . println ( str ) ; }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier))) (throws (type_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: (type_identifier) declarator: (variable_declarator name: (identifier) value: (string_literal))) (switch_expression condition: (parenthesized_expression (identifier)) body: (switch_block (switch_block_statement_group (switch_label (string_literal)) (expression_statement (assignment_expression left: (identifier) right: (string_literal))) (break_statement)) (switch_block_statement_group (switch_label (string_literal)) (expression_statement (assignment_expression left: (identifier) right: (string_literal))) (break_statement)) (switch_block_statement_group (switch_label (string_literal)) (expression_statement (assignment_expression left: (identifier) right: (string_literal))) (break_statement)) (switch_block_statement_group (switch_label (string_literal)) (expression_statement (assignment_expression left: (identifier) right: (string_literal))) (break_statement)) (switch_block_statement_group (switch_label) (break_statement)))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))