Fibonacci Guitar Tensions

You are given three integers representing the tensions of guitar strings. Your task is to determine whether there exists a permutation of these three integers that can form the first three numbers of a Fibonacci sequence. In a Fibonacci sequence, the largest number must equal the sum of the other two numbers, i.e., if the numbers (in sorted order) are \(a \leq b \leq c\), then they form a Fibonacci sequence if and only if \(c = a + b\). If such a permutation exists, output the largest tension; otherwise, output -1.

Note: The input is provided via the standard input and the output should be printed to the standard output.

inputFormat

The input consists of a single line containing three space-separated integers representing the guitar string tensions.

outputFormat

Output a single integer: the highest tension in the Fibonacci sequence if a valid permutation exists, or -1 if it does not.

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