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)

#[test]
fn test_solve() {
   assert_eq!(solve("<>>\n"), "3\n");
   assert_eq!(solve("<>>><<><<<<<>>><\n"), "28\n");
}

fn solve(src: &str) -> String {
    let mut sc = Scanner::from_str(src);

    let s: Vec<char> = sc.get().chars().collect();
    let n = s.len() + 1;
    let mut a = vec![0; n];
    
    for i in 0..n-1 {
        if s[i] == '<' {
            a[i+1] = a[i] + 1;
        }
    }
    for i in (0..n-1).rev() {
        if s[i] == '>' {
            a[i] = std::cmp::max(a[i], a[i+1] + 1);
        }
    }

    let sum: usize = a.iter().sum();

    format!("{}\n", sum)
}
fn main() {
    let mut buf = String::new();
    use std::io::{Read, Write};
    std::io::stdin().read_to_string(&mut buf).unwrap();
    std::io::stdout().write_all(solve(&buf).as_bytes()).unwrap();
}
struct Scanner<'a>(std::str::SplitWhitespace<'a>);
impl<'a> Scanner<'a> {
    fn from_str(src: &str) -> Scanner {
        Scanner(src.split_whitespace())
    }
    fn get(&mut self) -> &str {
        self.0.next().unwrap()
    }
    fn read<T: std::str::FromStr>(&mut self) -> T {
        self.get().parse().ok().unwrap()
    }
}