Given two coins of denominations X and Y respectively, find the largest amount that cannot be obtained using these two coins (assuming infinite supply of coins) followed by the total number of such non obtainable amounts.

Example 1:
Input: X = 2, Y = 5
Output: 3 2
Explanation: 3 is the largest amount that
can not be formed using 2 and 5. And there
are only 2 such non obtainable amounts and
they are 1 and 3.
Example 2:
Input: 5 10
Output: -1
Explanation: Using 5 and 10 there can be
infinite number of amounts that cannot be
formed.

Your Task:
You don't need to read or print anything. Your task is to complete the function frobenius() which takes X and Y as input parameters and returns a list of two numbers in which first number should be maximum amount that cannot be obtained and the second number should be total number of non-obtainable amounts. If no such value exist then returns a list containing -1.

Expected Time Complexity: O(log_{2}(max(X, Y)))
Expected Space Complexity: O(1)

Constraints:
2 <= X, Y <= 10000

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