public static void main ( String [ ] args ) throws IOException {
  BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ;
  BufferedWriter bw = new BufferedWriter ( new OutputStreamWriter ( System . out ) ) ;
  int n = Integer . parseInt ( br . readLine ( ) ) ;
  ArrayList < Integer > [ ] adj = new ArrayList [ n + 1 ] ;
  for ( int i = 0 ;
  i < ( n + 1 ) ;
  i ++ ) {
    adj [ i ] = new ArrayList < Integer > ( ) ;
  }
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    int j = Integer . parseInt ( br . readLine ( ) ) ;
    if ( j != - 1 ) {
      adj [ j ] . add ( i + 1 ) ;
    }
  }
  boolean [ ] visited = new boolean [ n + 1 ] ;
  int [ ] maxHeight = {
    0 };
    for ( int i = 1 ;
    i < n + 1 ;
    i ++ ) {
      if ( ! visited [ i ] ) {
        findMaxHeight ( i , 1 , adj , visited , maxHeight ) ;
      }
    }
    bw . write ( maxHeight [ 0 ] + "\n" ) ;
    bw . flush ( ) ;
  }
  
public static void main ( String [ ] args ) throws IOException { BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ; BufferedWriter bw = new BufferedWriter ( new OutputStreamWriter ( System . out ) ) ; int n = Integer . parseInt ( br . readLine ( ) ) ; ArrayList < Integer > [ ] adj = new ArrayList [ n + 1 ] ; for ( int i = 0 ; i < ( n + 1 ) ; i ++ ) { adj [ i ] = new ArrayList < Integer > ( ) ; } for ( int i = 0 ; i < n ; i ++ ) { int j = Integer . parseInt ( br . readLine ( ) ) ; if ( j != - 1 ) { adj [ j ] . add ( i + 1 ) ; } } boolean [ ] visited = new boolean [ n + 1 ] ; int [ ] maxHeight = { 0 } ; for ( int i = 1 ; i < n + 1 ; i ++ ) { if ( ! visited [ i ] ) { findMaxHeight ( i , 1 , adj , visited , maxHeight ) ; } } bw . write ( maxHeight [ 0 ] + " \n " ) ; bw . flush ( ) ; }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier))) (throws (type_identifier)) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (type_identifier) arguments: (argument_list (object_creation_expression type: (type_identifier) arguments: (argument_list (field_access object: (identifier) field: (identifier)))))))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (type_identifier) arguments: (argument_list (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 (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (local_variable_declaration type: (array_type element: (generic_type (type_identifier) (type_arguments (type_identifier))) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (type_identifier) dimensions: (dimensions_expr (binary_expression left: (identifier) right: (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: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal)))) update: (update_expression (identifier)) body: (block (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (object_creation_expression type: (generic_type (type_identifier) (type_arguments (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 (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (unary_expression operand: (decimal_integer_literal)))) consequence: (block (expression_statement (method_invocation object: (array_access array: (identifier) index: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))))))) (local_variable_declaration type: (array_type element: (boolean_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (boolean_type) dimensions: (dimensions_expr (binary_expression left: (identifier) right: (decimal_integer_literal)))))) (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_initializer (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: (binary_expression left: (identifier) right: (decimal_integer_literal))) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (unary_expression operand: (array_access array: (identifier) index: (identifier)))) consequence: (block (expression_statement (method_invocation name: (identifier) arguments: (argument_list (identifier) (decimal_integer_literal) (identifier) (identifier) (identifier)))))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (array_access array: (identifier) index: (decimal_integer_literal)) right: (string_literal))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))