Given two strings word1 and word2, return the minimum number of operations required to convert word1 to word2.

You have the following three operations permitted on a word:

• Insert a character
• Delete a character
• Replace a character

Examples

Example 1

Input:  word1 = "horse", word2 = "ros"
Output: 3

horse → rorse (replace 'h' with 'r') → rose (delete 'r') → ros (delete 'e')

Example 2

Input:  word1 = "intention", word2 = "execution"
Output: 5

Example 3

Input:  word1 = "", word2 = "abc"
Output: 3

Insert three characters.

Constraints

• 0 <= word1.length <= 500
• 0 <= word2.length <= 500
• word1 and word2 consist of lowercase English letters