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Задачи
1576. Simply syntax
Грамматики, рекурсивный разборОлимпиадные задачи на английском языке
| 27/02/1998 | Командные соревнования университета по программированию (6) |
| 04/07/2011 | Лето 2011 - дорешивание (04H) |
| 07/07/2011 | Лето 2011 - 4 (H) |
Ограничения: время – 1s/2s, память – 32MiB Ввод: input.txt или стандартный ввод Вывод: output.txt или стандартный вывод 
Послать решение Blockly Посылки Темы Где Обсудить (0)
In the land of Hedonia the official language is Hedonian. A Hedonian professor had
noticed that many of her students still did not master the syntax of Hedonian well.
Tired of correcting the many syntactical mistakes, she decided to
challenge the students and asked them to write a program that could
check the syntactical correctness of any sentence they wrote. Similar to the nature
of Hedonians, the syntax of Hedonian is also pleasantly simple. Here are the rules:
0. The only characters in the language are the characters p through z and N, C, D, E, and I.
1. Every character from p through z is a correct sentence.
2. If `s` is a correct sentence, then so is N`s`.
3. If `s` and `t` are correct sentences, then so are C`"st"`, D`"st"`, E`"st"` and I`"st"`.
4. Rules 0. to 3. are the only rules to determine the syntactical correctness of a sentence.
You are asked to write a program that checks if sentences satisfy the syntax rules given
in Rule 0. – Rule 4.
Input: The input consists of a number of sentences consisting only
of characters p through z and N, C, D, E, and I. Each sentence is ended
by a new-line character. The collection of sentences is terminated
by the end-of-file character. If necessary, you may assume that each
sentence has at most 256 characters and at least 1 character.
Output: The output consists of the answers YES for each well-formed
sentence and NO for each not-well-formed sentence.
The answers are given in the same order as the sentences.
Each answer is followed by a new-line character, and the list of answers
is followed by an end-of-file character.
Sample Input
Cp Isz NIsz Cqpq
Sample Output
NO YES YES NO
