public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  int [ ] ar = new int [ n + 1 ] ;
  Map < Integer , Long > map = new HashMap < Integer , Long > ( ) ;
  for ( int i = 1 ;
  i <= n ;
  i ++ ) {
    ar [ i ] = sc . nextInt ( ) ;
    int key = i - ar [ i ] ;
    if ( map . containsKey ( key ) ) {
      map . replace ( key , map . get ( key ) + ar [ i ] ) ;
    }
    else map . put ( key , ( long ) ar [ i ] ) ;
  }
  long max = 0 ;
  for ( Map . Entry < Integer , Long > entry : map . entrySet ( ) ) {
    max = Math . max ( max , entry . getValue ( ) ) ;
  }
  System . out . println ( ( long ) max ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; int [ ] ar = new int [ n + 1 ] ; Map < Integer , Long > map = new HashMap < Integer , Long > ( ) ; for ( int i = 1 ; i <= n ; i ++ ) { ar [ i ] = sc . nextInt ( ) ; int key = i - ar [ i ] ; if ( map . containsKey ( key ) ) { map . replace ( key , map . get ( key ) + ar [ i ] ) ; } else map . put ( key , ( long ) ar [ i ] ) ; } long max = 0 ; for ( Map . Entry < Integer , Long > entry : map . entrySet ( ) ) { max = Math . max ( max , entry . getValue ( ) ) ; } System . out . println ( ( long ) max ) ; }
(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 (binary_expression left: (identifier) right: (decimal_integer_literal)))))) (local_variable_declaration type: (generic_type (type_identifier) (type_arguments (type_identifier) (type_identifier))) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (generic_type (type_identifier) (type_arguments (type_identifier) (type_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 (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (array_access array: (identifier) index: (identifier))))) (if_statement condition: (parenthesized_expression (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))) consequence: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (array_access array: (identifier) index: (identifier))))))) alternative: (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (cast_expression type: (integral_type) value: (array_access array: (identifier) index: (identifier))))))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (enhanced_for_statement type: (generic_type (scoped_type_identifier (type_identifier) (type_identifier)) (type_arguments (type_identifier) (type_identifier))) name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) body: (block (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (cast_expression type: (integral_type) value: (identifier)))))))