A peak element is one that is strictly greater than its neighbors. Given an array nums, find a peak element and return its index. If the array contains multiple peaks, return any.

You must write an O(log n) solution.

Example 1:

Input: 1 2 3 1
Output: 2

Example 2:

Input: 1 2 1 3 5 6 4
Output: 5

Constraints:

• 1 ≤ nums.length ≤ 1000
• -2³¹ ≤ nums[i] ≤ 2³¹ - 1
• nums[i] ≠ nums[i+1]

Input format: Space-separated integers.

Output format: Index of any peak.