There are n people standing in a circle, numbered 1 to n. Starting from person 1, every k-th person is eliminated, continuing around the circle until one remains. Return the position (1-indexed) of the last survivor. Input: 'n, k'.
Input: 'n, k'.
Output: Integer — survivor position (1-indexed).
Input: 7, 3
Output: 4
Explanation: Survivor is position 4.Input: 5, 2
Output: 3
Explanation: Survivor is position 3.Input: 1, 1
Output: 1
Explanation: Only one person.1<=n<=10^51<=k<=10^5