Given a string consisting of lowercase letters only, find the typographically smallest string not present as a substring in it.
Given two string S1 and S2. S1 is considered typographically smaller than S2 if either:
∙|S1|<|S2|∙|S1|=|S2| and S1is lexicographically smaller than S2
Input:
The first line of input contains the string S.
Output:
Answer as stated above.
Constraints:
1≤|S|≤105
The given string saurabh , does not contain c hence answer is c.