public static void main ( String [ ] $ ) {
  Scanner sc = new Scanner ( in ) ;
  int n = sc . nextInt ( ) , m = sc . nextInt ( ) ;
  int [ ] a = new int [ m ] ;
  ArrayDeque < Integer > stack = new ArrayDeque < > ( ) ;
  for ( int i = n ;
  i > 0 ;
  i -- ) {
    stack . addFirst ( i ) ;
  }
  for ( int i = 0 ;
  i < m ;
  i ++ ) {
    a [ i ] = sc . nextInt ( ) ;
    stack . addFirst ( a [ i ] ) ;
  }
  int [ ] used = new int [ n + 1 ] ;
  while ( stack . size ( ) > 0 ) {
    int ans = stack . pollFirst ( ) ;
    if ( used [ ans ] == 0 ) {
      out . println ( ans ) ;
      used [ ans ] ++ ;
    }
  }
}

public static void main ( String [ ] $ ) { Scanner sc = new Scanner ( in ) ; int n = sc . nextInt ( ) , m = sc . nextInt ( ) ; int [ ] a = new int [ m ] ; ArrayDeque < Integer > stack = new ArrayDeque < > ( ) ; for ( int i = n ; i > 0 ; i -- ) { stack . addFirst ( i ) ; } for ( int i = 0 ; i < m ; i ++ ) { a [ i ] = sc . nextInt ( ) ; stack . addFirst ( a [ i ] ) ; } int [ ] used = new int [ n + 1 ] ; while ( stack . size ( ) > 0 ) { int ans = stack . pollFirst ( ) ; if ( used [ ans ] == 0 ) { out . println ( ans ) ; used [ ans ] ++ ; } } }
(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 (identifier))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (integral_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: (identifier))) condition: (binary_expression left: (identifier) right: (decimal_integer_literal)) update: (update_expression (identifier)) body: (block (expression_statement (method_invocation object: (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 (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (array_access array: (identifier) index: (identifier))))))) (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (binary_expression left: (identifier) right: (decimal_integer_literal)))))) (while_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) right: (decimal_integer_literal))) 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 (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (decimal_integer_literal))) consequence: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))) (expression_statement (update_expression (array_access array: (identifier) index: (identifier))))))))))