Problem:
Score : 300 points

Problem Statement

Given is a string S of length N-1.
Each character in S is < or >.

A sequence of N non-negative integers, a_1,a_2,\cdots,a_N, is said to be good when the following condition is satisfied for all i (1 \leq i \leq N-1):

If S_i= <: a_i<a_{i+1}

If S_i= >: a_i>a_{i+1}

Find the minimum possible sum of the elements of a good sequence of N non-negative integers.

Constraints

2 \leq N \leq 5 \times 10^5

S is a string of length N-1 consisting of < and >.

Input

Input is given from Standard Input in the following format:

S

Output

Find the minimum possible sum of the elements of a good sequence of N non-negative integers.

Sample Input 1

<>>

Sample Output 1

3

a=(0,2,1,0) is a good sequence whose sum is 3.
There is no good sequence whose sum is less than 3.

Sample Input 2

<>>><<><<<<<>>><

Sample Output 2

28

Solution in Rust (1.15.1) (judge verdict: Wrong Answer)

fn main() {
    let s = {
        let mut buf = String::new();
        std::io::stdin().read_line(&mut buf).unwrap();
        let mut s: Vec<char> = Vec::new();
        for c in buf.trim_right().to_owned().split_terminator(';') {
            match c {
                "&lt" => { s.push('<') },
                _ => { s.push('>') },
            }   
        }
        match s.first().unwrap() {
            &'<' => s.insert(0, '>'),
            _ => s.insert(0, '<'),
        };
        match s.last().unwrap() {
            &'<' => s.push('>'),
            _ => s.push('<'),
        };
        s.windows(2)
        .map(|cc| cc[0].to_string() + &cc[1].to_string() )
        .collect::<Vec<_>>()
    };
    println!("{:?}", s);
}