#K77942. Longest Palindromic Substring with Prime Length
Longest Palindromic Substring with Prime Length
Longest Palindromic Substring with Prime Length
You are given a list of strings. For each string, find the length of the longest substring that satisfies both of the following conditions:
- The length of the substring is a prime number. Recall that a number \( p \) is prime if \( p > 1 \) and its only divisors are 1 and \( p \); that is, there exists no \( d \) such that \( 1 < d < p \) and \( d \) divides \( p \).
- The substring is a palindrome; i.e. it reads the same forward and backward.
If no such substring exists in a given string, output -1.
Example: For the string "abacabad", one possible palindromic substring of prime length is "abacaba" of length 7 (since 7 is prime), so the answer is 7.
inputFormat
The first line contains an integer \( T \) denoting the number of test cases. Each of the following \( T \) lines contains a single string \( S \).
outputFormat
For each test case, output an integer on a new line representing the length of the longest palindromic substring whose length is a prime number. If there is no such substring, print -1.
## sample2
abacabad
abcde
7
-1
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