public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  boolean flag = false , imposible = false ;
  ArrayList < Integer > a = new ArrayList < Integer > ( ) ;
  ArrayList < Integer > b = new ArrayList < Integer > ( ) ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    b . add ( sc . nextInt ( ) ) ;
  }
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    for ( int j = b . size ( ) - 1 ;
    0 <= j ;
    j -- ) {
      if ( b . get ( j ) == j + 1 ) {
        a . add ( j + 1 ) ;
        b . remove ( j ) ;
        flag = true ;
        break ;
      }
    }
    if ( flag == false ) {
      imposible = true ;
      break ;
    }
    else {
      flag = false ;
    }
  }
  if ( imposible == true ) {
    System . out . println ( - 1 ) ;
  }
  else {
    for ( int i = a . size ( ) - 1 ;
    0 <= i ;
    i -- ) {
      System . out . println ( a . get ( i ) ) ;
    }
  }
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; boolean flag = false , imposible = false ; ArrayList < Integer > a = new ArrayList < Integer > ( ) ; ArrayList < Integer > b = new ArrayList < Integer > ( ) ; for ( int i = 0 ; i < n ; i ++ ) { b . add ( sc . nextInt ( ) ) ; } for ( int i = 0 ; i < n ; i ++ ) { for ( int j = b . size ( ) - 1 ; 0 <= j ; j -- ) { if ( b . get ( j ) == j + 1 ) { a . add ( j + 1 ) ; b . remove ( j ) ; flag = true ; break ; } } if ( flag == false ) { imposible = true ; break ; } else { flag = false ; } } if ( imposible == true ) { System . out . println ( - 1 ) ; } else { for ( int i = a . size ( ) - 1 ; 0 <= i ; i -- ) { System . out . println ( a . get ( i ) ) ; } } }
(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: (boolean_type) declarator: (variable_declarator name: (identifier) value: (false)) declarator: (variable_declarator name: (identifier) value: (false))) (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 (type_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 (type_identifier))) 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 (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) 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 (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: (decimal_integer_literal) right: (identifier)) 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 (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))) (expression_statement (assignment_expression left: (identifier) right: (true))) (break_statement))))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (false))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (true))) (break_statement)) alternative: (block (expression_statement (assignment_expression left: (identifier) right: (false))))))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (true))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (unary_expression operand: (decimal_integer_literal)))))) alternative: (block (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: (decimal_integer_literal) right: (identifier)) update: (update_expression (identifier)) body: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))))))))))