Unique Characters Check

Given a string s, determine whether all characters in the string are unique. In other words, check if for every pair of indices i and j where i ≠ j, the condition

$$s[i] \neq s[j]$$

holds. Print YES if all characters are unique, otherwise print NO.

Examples:

• If s = "abcdef", the output should be YES.
• If s = "aabbcc", the output should be NO.

Read the input from standard input and print the result to standard output.

inputFormat

The input consists of a single line containing the string s. The string may include any characters.

Note: The input is read from stdin.

outputFormat

Output a single line: YES if all characters in the string are unique; otherwise, output NO.

Note: The result should be printed to stdout.

abcdef

YES