public static void main ( String [ ] args ) {
  Scanner s = new Scanner ( System . in ) ;
  int x = 0 ;
  try {
    x = System . in . read ( ) ;
  }
  catch ( IOException e ) {
    System . err . println ( "????????" ) ;
  }
  System . out . println ( ( char ) x == 'A' ? "T" : ( char ) x == 'T' ? "A" : ( char ) x == 'C' ? "G" : "C" ) ;
}

public static void main ( String [ ] args ) { Scanner s = new Scanner ( System . in ) ; int x = 0 ; try { x = System . in . read ( ) ; } catch ( IOException e ) { System . err . println ( " ? ? ? ? ? ? ? ? " ) ; } System . out . println ( ( char ) x == ' A ' ? " T " : ( char ) x == ' T ' ? " A " : ( char ) x == ' C ' ? " G " : " C " ) ; }
(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: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (try_statement body: (block (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list))))) (catch_clause (catch_formal_parameter (catch_type (type_identifier)) name: (identifier)) body: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal))))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (ternary_expression condition: (binary_expression left: (cast_expression type: (integral_type) value: (identifier)) right: (character_literal)) consequence: (string_literal) alternative: (ternary_expression condition: (binary_expression left: (cast_expression type: (integral_type) value: (identifier)) right: (character_literal)) consequence: (string_literal) alternative: (ternary_expression condition: (binary_expression left: (cast_expression type: (integral_type) value: (identifier)) right: (character_literal)) consequence: (string_literal) alternative: (string_literal)))))))))