题目描述
Let N be a positive integer. You are given a string s of length N - 1, consisting of < and >.
Find the number of permutations $(p_1, p_2, \ldots, p_N)$ of $(1, 2, \ldots, N)$ that satisfy the following condition, modulo 10^9 + 7:
- For each $i (1 \leq i \leq N - 1), p_i < p_{i + 1}$ if the i-th character in s is
<, and p_i > p_{i + 1} if the i-th character in s is>.
Constraints
- N is an integer.
- $2 \leq N \leq 3000$
- s is a string of length N - 1.
- s consists of
<and>.
Input
Input is given from Standard Input in the following format:
N
s
Output
Print the number of permutations that satisfy the condition, modulo 10^9 + 7.
Examples
Input
4
<><
Output
5
Input
5
<<<<
Output
1
Input
20
<>>><>><>>><<>>
Output
217136290
输入格式
见题面
输出格式
见题面
样例输入
20
>>>><>>><>><>>><<>>
样例输出
217136290