public static void main ( String [ ] args ) throws IOException {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  ArrayList < Integer > rec = new ArrayList < > ( ) ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) rec . add ( sc . nextInt ( ) ) ;
  LinkedList < Integer > ans = new LinkedList < > ( ) ;
  while ( rec . size ( ) > 0 ) {
    int idx = - 1 ;
    for ( int i = rec . size ( ) - 1 ;
    i >= 0 ;
    i -- ) {
      if ( rec . get ( i ) == i + 1 ) {
        idx = i ;
        break ;
      }
    }
    if ( idx == - 1 ) break ;
    ans . addFirst ( rec . get ( idx ) ) ;
    rec . remove ( idx ) ;
  }
  if ( ans . size ( ) != n ) System . out . println ( - 1 ) ;
  else {
    for ( int w : ans ) System . out . println ( w ) ;
  }
}

public static void main ( String [ ] args ) throws IOException { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; ArrayList < Integer > rec = new ArrayList < > ( ) ; for ( int i = 0 ; i < n ; i ++ ) rec . add ( sc . nextInt ( ) ) ; LinkedList < Integer > ans = new LinkedList < > ( ) ; while ( rec . size ( ) > 0 ) { int idx = - 1 ; for ( int i = rec . size ( ) - 1 ; i >= 0 ; i -- ) { if ( rec . get ( i ) == i + 1 ) { idx = i ; break ; } } if ( idx == - 1 ) break ; ans . addFirst ( rec . get ( idx ) ) ; rec . remove ( idx ) ; } if ( ans . size ( ) != n ) System . out . println ( - 1 ) ; else { for ( int w : ans ) System . out . println ( w ) ; } }
(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: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (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: (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (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)))) (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: (unary_expression operand: (decimal_integer_literal)))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) right: (decimal_integer_literal)))) condition: (binary_expression left: (identifier) right: (decimal_integer_literal)) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (binary_expression left: (identifier) right: (decimal_integer_literal)))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (identifier))) (break_statement))))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (unary_expression operand: (decimal_integer_literal)))) consequence: (break_statement)) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))) (if_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) right: (identifier))) consequence: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (unary_expression operand: (decimal_integer_literal))))) alternative: (block (enhanced_for_statement type: (integral_type) name: (identifier) value: (identifier) body: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier)))))))))