public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  int m = sc . nextInt ( ) ;
  boolean [ ] a = new boolean [ n ] ;
  Deque < Integer > d = new ArrayDeque < > ( ) ;
  for ( int i = 0 ;
  i < m ;
  i ++ ) {
    int b = sc . nextInt ( ) ;
    d . push ( b ) ;
  }
  while ( ! d . isEmpty ( ) ) {
    int c = d . poll ( ) ;
    if ( ! a [ c - 1 ] ) {
      a [ c - 1 ] = true ;
      System . out . println ( c ) ;
    }
  }
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    if ( ! a [ i ] ) System . out . println ( i + 1 ) ;
  }
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; int m = sc . nextInt ( ) ; boolean [ ] a = new boolean [ n ] ; Deque < Integer > d = new ArrayDeque < > ( ) ; for ( int i = 0 ; i < m ; i ++ ) { int b = sc . nextInt ( ) ; d . push ( b ) ; } while ( ! d . isEmpty ( ) ) { int c = d . poll ( ) ; if ( ! a [ c - 1 ] ) { a [ c - 1 ] = true ; System . out . println ( c ) ; } } for ( int i = 0 ; i < n ; i ++ ) { if ( ! a [ i ] ) System . out . println ( i + 1 ) ; } }
(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: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (array_type element: (boolean_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (boolean_type) dimensions: (dimensions_expr (identifier))))) (local_variable_declaration type: (generic_type (type_identifier) (type_arguments (type_identifier))) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (generic_type (type_identifier) (type_arguments)) arguments: (argument_list)))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))) (while_statement condition: (parenthesized_expression (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) body: (block (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 (unary_expression operand: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))))) consequence: (block (expression_statement (assignment_expression left: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (true))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier)))))))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (unary_expression operand: (array_access array: (identifier) index: (identifier)))) consequence: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))))))))