Isogram Check
An isogram has no repeating characters. Is S an isogram?
Input: one line with the string S.
Output: YES or NO.
Constraints:
- 1 ≤ |S| ≤ 104
- S contains lowercase English letters
Sample Tests
Input 1
uncopyrightable
Output 1
YES
Input 2
hello
Output 2
NO
Discussion (opens after you solve — no spoilers before)
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