**The Challenge:**

Consider the function `F(N) = 2^N + 1` where `N` is a positive integer less than `31`. The sequence defined by this function is:

```
3, 5, 9, 17, 33, 65, 129, 257, 513, 1025, 2049, 4097, 8193, 16385, 32769, 65537, 131073, 262145, 524289, 1048577, 2097153, 4194305, 8388609, 16777217, 33554433, 67108865, 134217729, 268435457, 536870913, 1073741825

```

An input will be generated as follows:

* Take 5 *contiguous* integers from the above sequence.
* Replace one of them with a different, positive integer (which may or may not be part of the above sequence).
* Optionally reorder the the 5 resulting numbers.

Given such a list of 5 integers, find the one that was swapped in and is therefore not part of the original 5 contiguous integers.

Example:

* Original sublist: `5, 9, 17, 33, 65`.
* Replace one: `5, 7, 17, 33, 65`.
* Reorder: `33, 17, 5, 7, 65`.

The expected output would be `7`.

The 5 values in the input will always be distinct and there will always be a unique solution. (For instance, you won't have to deal with inputs like `3, 9, 17, 33, 129` where either `3` or `129` might have been swapped in.)

**Test Cases:**

```
5,9,17,33,829
o/p: 829

9,5,17,829,33
o/p: 829

33, 17, 5, 7, 65
o/p: 7

5,9,177,33,65
o/p: 177

65,129,259,513,1025
o/p: 259

129,259,513,1025,65
o/p: 259

63,129,257,513,1025
o/p: 63

65,129,257,513,4097
o/p: 4097

5, 9, 2, 17, 33
o/p: 2

536870913, 67108865, 1073741825, 1, 268435457
o/p: 1

```