public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  while ( sc . hasNextInt ( ) ) {
    int n = sc . nextInt ( ) ;
    while ( n -- > 0 ) {
      int l = sc . nextInt ( ) ;
      int r = sc . nextInt ( ) ;
      if ( 2 * l <= r ) {
        System . out . printf ( "%d %d\n" , l , 2 * l ) ;
      }
      else {
        System . out . print ( "-1 -1\n" ) ;
      }
    }
  }
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; while ( sc . hasNextInt ( ) ) { int n = sc . nextInt ( ) ; while ( n -- > 0 ) { int l = sc . nextInt ( ) ; int r = sc . nextInt ( ) ; if ( 2 * l <= r ) { System . out . printf ( " % d ▁ % d \n " , l , 2 * l ) ; } else { System . out . print ( " - 1 ▁ - 1 \n " ) ; } } } }
(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)))))) (while_statement condition: (parenthesized_expression (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)))) (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: (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: (binary_expression left: (decimal_integer_literal) right: (identifier)) right: (identifier))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal) (identifier) (binary_expression left: (decimal_integer_literal) right: (identifier)))))) alternative: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal))))))))))))