Word Search II

Given a grid of letters and a list of words, find all words from the list that can be formed by sequentially adjacent letters (horizontally or vertically) in the grid. Words may not use the same letter cell more than once. Input format: The first line contains two integers m and n, the dimensions of the grid. The next m lines contain n characters each, followed by an integer k on the next line and k words. Output format: A list of found words. Example: Input: 2 2 ab cd 2 ab cd Output: ['ab', 'cd']