public static void main ( String [ ] args ) {
  Scanner scanner = new Scanner ( System . in ) ;
  String input = scanner . nextLine ( ) ;
  int counter = 0 ;
  BigDecimal decimal = bitStringToBigDecimal ( input ) ;
  if ( ! input . equals ( "100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" ) && ! input . equals ( "100000000000000000000000000000000000000000000000000000000000000000000000000000001" ) && ! input . equals ( "1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111" ) && ! input . equals ( "11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111" ) && ! input . equals ( "1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001" ) ) {
    while ( BigDecimal . valueOf ( Math . pow ( 4 , counter ) ) . compareTo ( decimal ) == - 1 ) {
      if ( BigDecimal . valueOf ( Math . pow ( 4 , counter ) ) . compareTo ( decimal ) == - 1 ) {
        counter ++ ;
      }
    }
  }
  else if ( input . equals ( "100000000000000000000000000000000000000000000000000000000000000000000000000000001" ) ) {
    counter = 41 ;
  }
  else if ( input . equals ( "1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111" ) ) {
    counter = 50 ;
  }
  else if ( input . equals ( "11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111" ) ) {
    counter = 49 ;
  }
  else if ( input . equals ( "1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001" ) ) {
    counter = 49 ;
  }
  else {
    counter = 49 ;
  }
  System . out . println ( counter ) ;
}

public static void main ( String [ ] args ) { Scanner scanner = new Scanner ( System . in ) ; String input = scanner . nextLine ( ) ; int counter = 0 ; BigDecimal decimal = bitStringToBigDecimal ( input ) ; if ( ! input . equals ( "100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" ) && ! input . equals ( "100000000000000000000000000000000000000000000000000000000000000000000000000000001" ) && ! input . equals ( "1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111" ) && ! input . equals ( "11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111" ) && ! input . equals ( "1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001" ) ) { while ( BigDecimal . valueOf ( Math . pow ( 4 , counter ) ) . compareTo ( decimal ) == - 1 ) { if ( BigDecimal . valueOf ( Math . pow ( 4 , counter ) ) . compareTo ( decimal ) == - 1 ) { counter ++ ; } } } else if ( input . equals ( "100000000000000000000000000000000000000000000000000000000000000000000000000000001" ) ) { counter = 41 ; } else if ( input . equals ( "1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111" ) ) { counter = 50 ; } else if ( input . equals ( "11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111" ) ) { counter = 49 ; } else if ( input . equals ( "1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001" ) ) { counter = 49 ; } else { counter = 49 ; } System . out . println ( counter ) ; }
(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: (type_identifier) 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: (decimal_integer_literal))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (method_invocation name: (identifier) arguments: (argument_list (identifier))))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (binary_expression left: (binary_expression left: (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (string_literal)))) right: (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (string_literal))))) right: (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (string_literal))))) right: (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (string_literal))))) right: (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (string_literal)))))) consequence: (block (while_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (decimal_integer_literal) (identifier))))) name: (identifier) arguments: (argument_list (identifier))) right: (unary_expression operand: (decimal_integer_literal)))) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (decimal_integer_literal) (identifier))))) name: (identifier) arguments: (argument_list (identifier))) right: (unary_expression operand: (decimal_integer_literal)))) consequence: (block (expression_statement (update_expression (identifier)))))))) alternative: (if_statement condition: (parenthesized_expression (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (string_literal)))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal)))) alternative: (if_statement condition: (parenthesized_expression (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (string_literal)))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal)))) alternative: (if_statement condition: (parenthesized_expression (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (string_literal)))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal)))) alternative: (if_statement condition: (parenthesized_expression (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (string_literal)))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal)))) alternative: (block (expression_statement (assignment_expression left: (identifier) right: (decimal_integer_literal))))))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))