OnlineJudge 3 现已推出。点此体验新版：Conflict | SDUT OnlineJudge

### Conflict

Time Limit: 1000 ms
Memory Limit: 65536 KiB

#### Problem Description

Given several formula like "variable1 relation variable2", where relation may be <,<=,=,!=,>=,>, variables may contain up to 10 letters or digits and are case-sensitive. Please determine whether there is a conflict.

#### Input

There are several cases. Each case begins with a line "Case%n:"(%n is the case number), and contains several formulas, one per line. There are no more than 100 formulas for each case. Please see sample input for more details. Input is teminated by EOF.

#### Output

If there is no conflict, output"YES", otherwise, output"NO". Please refer to sample output for the exact output format.

#### Sample Input

Case1: xyz < 123 123 < 45 Case2: x < y y < x

#### Sample Output

Case1: YES Case2: NO

#### Hint

#### Source

第9届中山大学程序设计竞赛预选赛