5 人解决，11 人已尝试。
5 份提交通过，共有 20 份提交。
8.0 EMB 奖励。
单点时限: 2.0 sec
内存限制: 256 MB
Surely you know someone who thinks he is very clever. You decide to let him down with the following problem:
“Can you tell me what the syntax for a set is?”, you ask him.
“Sure!”, he replies, “a set encloses a possibly empty list of elements within two curly braces. Each element is either another set or a letter of the given alphabet. Elements in a list are separated by a comma.”
“So if I give you a word, can you tell me if it is a syntactically correct representation of a set?”
“Of course, any fool can do it!” is his answer.
Now you got him! You present him with the following grammar, defining formally the syntax for a set (which was described informally by him):
Set ::= “{” Elementlist “}”
Elementlist ::=
List ::= Element | Element “,” List
Element ::= Atom | Set
Atom ::= “{” | “}” | “,”
Soon he realizes that this task is much harder than he has thought, since the alphabet consists of the characters which are also used for the syntax of the set. So he claims that it is not possible to decide efficiently if a word consisting of “{“, “}” and “,” is a syntactically correct representation of a set or not.
To disprove him, you need to write an efficient program that will decide this problem.
The first line of the input contains a number representing the number of lines to follow.
Each line consists of a word, for which your program has to decide if it is a syntactically correct representation of a set. You may assume that each word consists of between 1 and 200 characters from the set { “{“, “}”, “,” }.
Output for each test case whether the word is a set or not. Adhere to the format shown in the sample output.
4
{}
{{}}
{{}},{,}}
{,,}
Word #1: Set Word #2: Set Word #3: Set Word #4: No Set
5 人解决，11 人已尝试。
5 份提交通过，共有 20 份提交。
8.0 EMB 奖励。