##### Short Problem Definition:

Find a symmetry point of a string, if any.

##### Link

##### Complexity:

expected worst-case time complexity is `O(length(S))`

expected worst-case space complexity is `O(1)`

(not counting the storage required for input arguments).

##### Execution:

This problem gave me a lot of headache. It is so trivial I that over-complicated it. I thought that you should find a symmetry point at any possible position, ignoring the residual characters. You would obviously try to maximize the length of this symmetrical sub-array. I was not able to come with any O(S) algorithm for this problem derivation. So just to remind you, **this problem is a simple palindrome check**. Additionally, you drop all evenly sized strings as their symmetry point is between the indexes.

##### Solution:

```
def solution(S):
l = len(S)
if l % 2 == 0:
return -1
mid_point = l // 2
for idx in xrange(0, mid_point):
if S[idx] != S[l - idx - 1]:
return -1
return mid_point
```