public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  int x = n ;
  int y = 1 ;
  int sum = 0 ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    sum += x * y ;
    x -- ;
    y ++ ;
  }
  n -- ;
  sum -= ( n * ( n + 1 ) ) / 2 ;
  System . out . println ( sum ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; int x = n ; int y = 1 ; int sum = 0 ; for ( int i = 0 ; i < n ; i ++ ) { sum += x * y ; x -- ; y ++ ; } n -- ; sum -= ( n * ( n + 1 ) ) / 2 ; System . out . println ( sum ) ; }
(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: (integral_type) declarator: (variable_declarator name: (identifier) value: (identifier))) (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))) (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: (identifier) right: (binary_expression left: (identifier) right: (identifier)))) (expression_statement (update_expression (identifier))) (expression_statement (update_expression (identifier))))) (expression_statement (update_expression (identifier))) (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (parenthesized_expression (binary_expression left: (identifier) right: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))))) right: (decimal_integer_literal)))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))