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)

use std::cmp::{max, min};

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn main() {
    let a: Vec<char> = read::<String>().chars().collect();
    let n = a.len();
    let mut v = vec![('<', 1)];
    let mut pos = 0;
    while pos < n {
        let c = a[pos];
        let count = take_while(c, &a, pos);
        v.push((c, count));
        pos += count;
    }

    v.push(('>', 1));
    let m = v.len();
    let mut ans: usize = 0;
    for i in 0..m - 1 {
        if !(v[i].0 == '<' && v[i + 1].0 == '>') {
            continue;
        }

        let l = max(v[i].1, v[i + 1].1);
        let r = min(v[i].1, v[i + 1].1);
        ans += (l * (l + 1)) / 2 + ((r - 1) * r) / 2;
    }

    println!("{}", ans);
}

fn take_while(c: char, s: &Vec<char>, pos: usize) -> usize {
    let n = s.len();
    let mut ret = 0;
    for i in pos..n {
        if s[i] != c {
            break;
        }
        ret += 1;
    }
    ret
}