"""   Given n, how many structurally unique BST's (binary search trees) that store
   values 1 ... n? Example: Input: 3 Output: 5 Explanation: Given n = 3, there
   are a total of 5 unique BST's:
   
        1
        
        1         2
         \       /
          2     1
   
        1      3       3      2    1 
         \    /       /      / \    \ 
          3  2       1      1   3    2
         /  /         \               \ 
        2  1           2               3 
        
        Constraints: 1 <= n <= 19
"""

class Solution96:
    pass
