preorder : 50,27,16,4,12,34,29,44,88,65,52,77,93,92
postorder :12,4,16,29,44,34,27,52,77,65,92,93,88,50
now, we apply algorithm to 14 * 14 table (fill them using longest commomn subsequence algorithm)
then we find longest common subsequence is 12,29,44,52,77,92