Fibonacci Prime Replacement

In this problem, you are given an integer ( n ) and you need to compute the ( n )th Fibonacci number according to the recurrence ( F_0 = 0,; F_1 = 1,; F_n = F_{n-1} + F_{n-2} ) for ( n \ge 2 ). However, if the computed Fibonacci number is a prime number, you should output (-1) instead of the number. If ( n ) is negative, output the string "None". Solve this problem using standard input and output.

inputFormat

A single line containing an integer ( n ) (( n ) can be negative). The input is given via standard input (stdin).

outputFormat

Print the ( n )th Fibonacci number if it is not a prime. If it is prime, print (-1). For a negative ( n ), print "None". The output should be sent to standard output (stdout).## sample

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