Remove Duplicate Characters

Given a string S, remove all duplicate characters while preserving the order of their first appearance. For example, if S is abbacccd, then the output should be abcd. Use the \(\text{removeDuplicates}\) logic to solve the problem.

The task is simple: iterate through the input string, and record each character the first time it appears. If a character has already been seen, skip it. Finally, output the result.

Note: The input will be provided via standard input (stdin) and the resulting string should be printed to standard output (stdout).

inputFormat

The input consists of a single line containing a string \(S\) which may include alphabets, digits, and symbols. The length of \(S\) can be up to \(10^5\) characters.

outputFormat

Output a single string that has all the duplicates removed from \(S\) and the original order preserved.

abbacccd

abcd