public static void main ( String [ ] args ) {
  Scanner in = new Scanner ( System . in ) ;
  a = in . nextInt ( ) ;
  b = in . nextInt ( ) ;
  x = in . nextInt ( ) ;
  y = in . nextInt ( ) ;
  l = 1 ;
  r = 10000000000l ;
  while ( l <= r ) {
    mid = ( l + r ) / 2 ;
    if ( mid - mid / x >= a && mid - mid / y >= b && mid - mid / x / y >= a + b ) {
      ans = mid ;
      r = mid - 1 ;
    }
    else l = mid + 1 ;
  }
  System . out . println ( ans ) ;
}

public static void main ( String [ ] args ) { Scanner in = new Scanner ( System . in ) ; a = in . nextInt ( ) ; b = in . nextInt ( ) ; x = in . nextInt ( ) ; y = in . nextInt ( ) ; l = 1 ; r = 10000000000l ; while ( l <= r ) { mid = ( l + r ) / 2 ; if ( mid - mid / x >= a && mid - mid / y >= b && mid - mid / x / y >= a + b ) { ans = mid ; r = mid - 1 ; } else l = mid + 1 ; } System . out . println ( ans ) ; }
(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)))))) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal))) (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal))) (while_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) body: (block (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) right: (decimal_integer_literal)))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (binary_expression left: (binary_expression left: (identifier) right: (binary_expression left: (identifier) right: (identifier))) right: (identifier)) right: (binary_expression left: (binary_expression left: (identifier) right: (binary_expression left: (identifier) right: (identifier))) right: (identifier))) right: (binary_expression left: (binary_expression left: (identifier) right: (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (identifier))) right: (binary_expression left: (identifier) right: (identifier))))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (identifier))) (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (identifier) right: (decimal_integer_literal))))) alternative: (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (identifier) right: (decimal_integer_literal))))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))