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: Accepted)

fn run_length_encoding<T: Clone + Eq>(a: &[T]) -> Vec<(T, usize)> {
    if a.len() == 0 {
        return vec![];
    }
    let mut x = a[0].clone();
    let mut cnt = 1;
    let mut ans = vec![];
    for y in &a[1..] {
        if x == *y {
            cnt += 1;
        } else {
            ans.push((x, cnt));
            x = y.clone();
            cnt = 1;
        }
    }
    ans.push((x, cnt));
    ans
}

fn run() {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    let s: Vec<char> = s.trim().chars().collect();
    let a = run_length_encoding(&s);
    let mut ans = a.iter().fold(0, |s, a| s + a.1 * (a.1 + 1) / 2);
    for i in 1..a.len() {
        if a[i - 1].0 == '<' && a[i].0 == '>' {
            ans -= std::cmp::min(a[i - 1].1, a[i].1);
        }
    }
    println!("{}", ans);
}

fn main() {
    run();
}