public static void main ( String [ ] args ) {
  Scanner scanner = new Scanner ( System . in ) ;
  int t = scanner . nextInt ( ) ;
  for ( int i = 0 ;
  i < t ;
  i ++ ) {
    int l = scanner . nextInt ( ) , r = scanner . nextInt ( ) ;
    if ( r == 2 && l == 1 ) {
      System . out . println ( l + " " + r ) ;
      continue ;
    }
    if ( ( r - l ) == 1 || l > r / 2 ) {
      System . out . println ( - 1 + " " + ( - 1 ) ) ;
    }
    else {
      if ( r % 2 == 0 ) {
        System . out . println ( r / 2 + " " + r ) ;
      }
      else {
        System . out . println ( ( r - 1 ) / 2 + " " + ( r - 1 ) ) ;
      }
    }
  }
}

public static void main ( String [ ] args ) { Scanner scanner = new Scanner ( System . in ) ; int t = scanner . nextInt ( ) ; for ( int i = 0 ; i < t ; i ++ ) { int l = scanner . nextInt ( ) , r = scanner . nextInt ( ) ; if ( r == 2 && l == 1 ) { System . out . println ( l + " ▁ " + r ) ; continue ; } if ( ( r - l ) == 1 || l > r / 2 ) { System . out . println ( - 1 + " ▁ " + ( - 1 ) ) ; } else { if ( r % 2 == 0 ) { System . out . println ( r / 2 + " ▁ " + r ) ; } else { System . out . println ( ( r - 1 ) / 2 + " ▁ " + ( r - 1 ) ) ; } } } }
(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)))) (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 (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)))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (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: (binary_expression left: (identifier) right: (string_literal)) right: (identifier))))) (continue_statement))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) right: (decimal_integer_literal)) right: (binary_expression left: (identifier) right: (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: (binary_expression left: (unary_expression operand: (decimal_integer_literal)) right: (string_literal)) right: (parenthesized_expression (unary_expression operand: (decimal_integer_literal)))))))) alternative: (block (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) 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: (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (string_literal)) right: (identifier)))))) alternative: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (binary_expression left: (binary_expression left: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (decimal_integer_literal)) right: (string_literal)) right: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal)))))))))))))))