public static void main ( String args [ ] ) {
  Scanner s = new Scanner ( System . in ) ;
  int t = s . nextInt ( ) ;
  while ( t -- != 0 ) {
    int n = s . nextInt ( ) ;
    TreeSet < Integer > pq = new TreeSet < > ( ) ;
    int arr [ ] = new int [ n ] ;
    int ans = 0 ;
    for ( int i = 0 ;
    i < n ;
    i ++ ) {
      arr [ i ] = s . nextInt ( ) ;
      if ( arr [ i ] < i + 1 ) {
        ans = - 1 ;
      }
      pq . add ( i + 1 ) ;
    }
    if ( ans == - 1 ) {
      System . out . println ( ans ) ;
    }
    else {
      System . out . print ( arr [ 0 ] + " " ) ;
      pq . remove ( arr [ 0 ] ) ;
      for ( int i = 1 ;
      i < n ;
      i ++ ) {
        if ( arr [ i ] > arr [ i - 1 ] ) {
          System . out . print ( arr [ i ] + " " ) ;
          pq . remove ( arr [ i ] ) ;
        }
        else {
          System . out . print ( pq . pollFirst ( ) + " " ) ;
        }
      }
      System . out . println ( ) ;
    }
  }
}

public static void main ( String args [ ] ) { Scanner s = new Scanner ( System . in ) ; int t = s . nextInt ( ) ; while ( t -- != 0 ) { int n = s . nextInt ( ) ; TreeSet < Integer > pq = new TreeSet < > ( ) ; int arr [ ] = new int [ n ] ; int ans = 0 ; for ( int i = 0 ; i < n ; i ++ ) { arr [ i ] = s . nextInt ( ) ; if ( arr [ i ] < i + 1 ) { ans = - 1 ; } pq . add ( i + 1 ) ; } if ( ans == - 1 ) { System . out . println ( ans ) ; } else { System . out . print ( arr [ 0 ] + " ▁ " ) ; pq . remove ( arr [ 0 ] ) ; for ( int i = 1 ; i < n ; i ++ ) { if ( arr [ i ] > arr [ i - 1 ] ) { System . out . print ( arr [ i ] + " ▁ " ) ; pq . remove ( arr [ i ] ) ; } else { System . out . print ( pq . pollFirst ( ) + " ▁ " ) ; } } System . out . println ( ) ; } } }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (type_identifier) name: (identifier) dimensions: (dimensions))) 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)))) (while_statement condition: (parenthesized_expression (binary_expression left: (update_expression (identifier)) 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)))) (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)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) dimensions: (dimensions) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (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)))) (if_statement condition: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (binary_expression left: (identifier) right: (decimal_integer_literal)))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (unary_expression operand: (decimal_integer_literal)))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (unary_expression operand: (decimal_integer_literal)))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))) alternative: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (array_access array: (identifier) index: (decimal_integer_literal)) right: (string_literal))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (array_access array: (identifier) index: (decimal_integer_literal))))) (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 (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal))))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (string_literal))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (array_access array: (identifier) index: (identifier)))))) alternative: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) right: (string_literal))))))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list)))))))))