public static void main ( String [ ] args ) {
  Scanner input = new Scanner ( System . in ) ;
  int n = input . nextInt ( ) ;
  String s = input . next ( ) ;
  int d = - 1 ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    if ( s . charAt ( i ) == '1' ) {
      if ( d == - 1 ) {
        if ( i >= 2 ) {
          System . out . println ( "NO" ) ;
          return ;
        }
      }
      else if ( i - d == 1 || i - d > 3 ) {
        System . out . println ( "NO" ) ;
        return ;
      }
      d = i ;
    }
  }
  if ( n - d > 2 || d == - 1 ) {
    System . out . println ( "NO" ) ;
  }
  else {
    System . out . println ( "YES" ) ;
  }
}

public static void main ( String [ ] args ) { Scanner input = new Scanner ( System . in ) ; int n = input . nextInt ( ) ; String s = input . next ( ) ; int d = - 1 ; for ( int i = 0 ; i < n ; i ++ ) { if ( s . charAt ( i ) == '1' ) { if ( d == - 1 ) { if ( i >= 2 ) { System . out . println ( " NO " ) ; return ; } } else if ( i - d == 1 || i - d > 3 ) { System . out . println ( " NO " ) ; return ; } d = i ; } } if ( n - d > 2 || d == - 1 ) { System . out . println ( " NO " ) ; } else { System . out . println ( " YES " ) ; } }
(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: (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: (unary_expression operand: (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 (if_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (character_literal))) consequence: (block (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (unary_expression operand: (decimal_integer_literal)))) consequence: (block (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal)))) (return_statement)))) alternative: (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (decimal_integer_literal)) right: (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (decimal_integer_literal)))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal)))) (return_statement)))) (expression_statement (assignment_expression left: (identifier) right: (identifier))))))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (decimal_integer_literal)) right: (binary_expression left: (identifier) right: (unary_expression operand: (decimal_integer_literal))))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal))))) alternative: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal))))))))