How Many Trees?[HDU1130]

How Many Trees?

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 2435    Accepted Submission(s): 1404

Problem Description
A binary search tree is a binary tree with root k such that any node v reachable from its left has label (v) <label (k) and any node w reachable from its right has label (w) > label (k). It is a search structure which can find a node with label x in O(n log n) average time, where n is the size of the tree (number of vertices).

Given a number n, can you tell how many different binary search trees may be constructed with a set of numbers of size n such that each element of the set will be associated to the label of exactly one node in a binary search tree?

Input
The input will contain a number 1 <= i <= 100 per line representing the number of elements of the set.

Output
You have to print a line in the output for each entry with the answer to the previous question.

Sample Input
1
2
3

Sample Output
1
2
5

Source
UVA

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Eddy

catalan数的应用,要用高精度,懒得写了.