You are given an m x n matrix of heights. A route's effort is the maximum absolute difference in heights between two consecutive cells along the route.

Return the minimum effort required to travel from the top-left to the bottom-right cell.

Example 1:

Input: heights = [[1,2,2],[3,8,2],[5,3,5]]
Output: 2

Example 2:

Input: heights = [[1,2,3],[3,8,4],[5,3,5]]
Output: 1

Constraints:

• m == heights.length
• n == heights[i].length
• 1 <= m, n <= 100