Given an array of strings arr of size n, determine an array of strings answer of length n such that for each index i:

• answer[i] is the shortest substring of arr[i] that does not appear as a substring in any other string in arr.

• If there are multiple such shortest substrings, answer[i] is the lexicographically smallest one.

• If no such substring exists, answer[i] is an empty string "".

Return the array answer.

Constraints:

• n $==$ arr.length

• $2 \leq$ n $\leq 100$

• $1 \leq$ arr[i].length $\leq 20$

• arr[i] consists only of lowercase English letters.

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