public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  int [ ] [ ] array = new int [ n ] [ 2 ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    array [ i ] [ 0 ] = sc . nextInt ( ) ;
    array [ i ] [ 1 ] = sc . nextInt ( ) ;
  }
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    switch ( array [ i ] [ 0 ] ) {
      case 1 : System . out . println ( 0 ) ;
      break ;
      case 2 : System . out . println ( array [ i ] [ 1 ] ) ;
      break ;
      default : System . out . println ( array [ i ] [ 1 ] * 2 ) ;
      break ;
    }
  }
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; int [ ] [ ] array = new int [ n ] [ 2 ] ; for ( int i = 0 ; i < n ; i ++ ) { array [ i ] [ 0 ] = sc . nextInt ( ) ; array [ i ] [ 1 ] = sc . nextInt ( ) ; } for ( int i = 0 ; i < n ; i ++ ) { switch ( array [ i ] [ 0 ] ) { case 1 : System . out . println ( 0 ) ; break ; case 2 : System . out . println ( array [ i ] [ 1 ] ) ; break ; default : System . out . println ( array [ i ] [ 1 ] * 2 ) ; break ; } } }
(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: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier)) dimensions: (dimensions_expr (decimal_integer_literal))))) (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 (assignment_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (decimal_integer_literal)) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (assignment_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (decimal_integer_literal)) right: (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 (switch_expression condition: (parenthesized_expression (array_access array: (array_access array: (identifier) index: (identifier)) index: (decimal_integer_literal))) body: (switch_block (switch_block_statement_group (switch_label (decimal_integer_literal)) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (decimal_integer_literal)))) (break_statement)) (switch_block_statement_group (switch_label (decimal_integer_literal)) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (array_access array: (array_access array: (identifier) index: (identifier)) index: (decimal_integer_literal))))) (break_statement)) (switch_block_statement_group (switch_label) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (decimal_integer_literal)) right: (decimal_integer_literal))))) (break_statement))))))))