Valid Hexadecimal

Difficulty: 900 2000 ms 128 MB

implementation strings

Is S a plain hexadecimal string — only digits and letters a–f/A–F, no prefix?

Input: one line with the candidate string S.

Output: YES or NO.

Constraints:

• 1 ≤ |S| ≤ 100

Sample Tests

1A3f

YES

0x1A

NO

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