public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    long x = sc . nextInt ( ) ;
    long y = sc . nextInt ( ) ;
    long p = sc . nextInt ( ) ;
    long q = sc . nextInt ( ) ;
    if ( ! works ( x , y , p , q , 1000000000 ) ) {
      System . out . println ( - 1 ) ;
      continue ;
    }
    long l = 0 ;
    long r = 1000000000 ;
    while ( r > l ) {
      long mid = ( r + l ) / 2 ;
      if ( works ( x , y , p , q , mid ) ) r = mid ;
      else l = mid + 1 ;
    }
    System . out . println ( r * q - y ) ;
  }
  sc . close ( ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; for ( int i = 0 ; i < n ; i ++ ) { long x = sc . nextInt ( ) ; long y = sc . nextInt ( ) ; long p = sc . nextInt ( ) ; long q = sc . nextInt ( ) ; if ( ! works ( x , y , p , q , 1000000000 ) ) { System . out . println ( - 1 ) ; continue ; } long l = 0 ; long r = 1000000000 ; while ( r > l ) { long mid = ( r + l ) / 2 ; if ( works ( x , y , p , q , mid ) ) r = mid ; else l = mid + 1 ; } System . out . println ( r * q - y ) ; } sc . close ( ) ; }
(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)))) (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)))) (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 (unary_expression operand: (method_invocation name: (identifier) arguments: (argument_list (identifier) (identifier) (identifier) (identifier) (decimal_integer_literal))))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (unary_expression operand: (decimal_integer_literal))))) (continue_statement))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (while_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) body: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) right: (decimal_integer_literal)))) (if_statement condition: (parenthesized_expression (method_invocation name: (identifier) arguments: (argument_list (identifier) (identifier) (identifier) (identifier) (identifier)))) consequence: (expression_statement (assignment_expression left: (identifier) right: (identifier))) 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 (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (identifier))))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))