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 (1.42.0) (judge verdict: Accepted)

use whiteread::parse_line;

fn main() {
    let s: String = parse_line().unwrap();
    let mut s: Vec<char> = s.chars().collect();
    s.push('<');
    let mut left = s[0];
    let mut ans: Vec<[usize; 2]> = Vec::new();
    let mut cnt = [0, 0];

    for i in 1..s.len() {
        match (left, s[i]) {
            ('<', '<') => cnt[0] += 1,
            ('<', '>') => {
                cnt[0] += 1;
                left = '>';
            }
            ('>', '>') => cnt[1] += 1,
            ('>', '<') => {
                cnt[1] += 1;
                left = '<';
                ans.push(cnt);
                cnt = [0, 0];
            }
            _ => unreachable!(),
        }
    }
    ans.push(cnt);
    println!(
        "{}",
        ans.iter().fold(0, |x, y| x
            + (0..=y[0].max(y[1])).sum::<usize>()
            + (0..=y[0].min(y[1])).sum::<usize>()
            - y[0].min(y[1]))
    );
}