public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  int p = 0 ;
  String s = sc . next ( ) ;
  for ( int i = 0 ;
  i < s . length ( ) - 1 ;
  i ++ ) {
    for ( int j = i + 1 ;
    j < s . length ( ) ;
    j ++ ) {
      if ( s . charAt ( i ) != s . charAt ( j ) ) {
        continue ;
      }
      else {
        p ++ ;
        break ;
      }
    }
  }
  if ( n == 1 ) {
    System . out . println ( "YES" ) ;
  }
  else {
    System . out . println ( p > 0 ? "YES" : "NO" ) ;
  }
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; int p = 0 ; String s = sc . next ( ) ; for ( int i = 0 ; i < s . length ( ) - 1 ; i ++ ) { for ( int j = i + 1 ; j < s . length ( ) ; j ++ ) { if ( s . charAt ( i ) != s . charAt ( j ) ) { continue ; } else { p ++ ; break ; } } } if ( n == 1 ) { System . out . println ( " YES " ) ; } else { System . out . println ( p > 0 ? " YES " : " NO " ) ; } }
(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: (decimal_integer_literal))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (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: (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) right: (decimal_integer_literal))) update: (update_expression (identifier)) body: (block (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (decimal_integer_literal)))) condition: (binary_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) 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: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))) consequence: (block (continue_statement)) alternative: (block (expression_statement (update_expression (identifier))) (break_statement))))))) (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))))) alternative: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (ternary_expression condition: (binary_expression left: (identifier) right: (decimal_integer_literal)) consequence: (string_literal) alternative: (string_literal)))))))))