Python (Simple Maths)
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\nclass Solution:\n    def minDeletionSize(self, strs):\n        n, m, total = len(strs), len(strs[0]), 0\n        unsorted = set(range(n-1))\n\n        for j in range(m):\n            if any(strs[i][j] > strs[i+1][j] for i in unsorted):\n                total += 1 \n            else:\n                unsorted -= {i for i in unsorted if strs[i][j] < strs[i+1][j]}\n\n        return total \n```
['Python3']