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)

pub 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()
}

pub fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}

pub fn read_vec2<T: std::str::FromStr>(n: usize) -> Vec<Vec<T>> {
    (0..n).map(|_| read_vec()).collect()
}

pub fn read_col<T: std::str::FromStr>(n: usize) -> Vec<T> {
    (0..n).map(|_| read()).collect()
}

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

fn main() {
    let s: String = read();
    let cv: Vec<char> = s.chars().collect();

    let mut cntv: Vec<u64> = vec![];

    let mut idx: u64 = 0;
    let mut tmp: u64 = 0;
    'l: loop {
        let l = cv.len() as u64;
        loop {
            if idx >= l || cv[idx as usize] != '<' {
                break;
            }
            idx += 1;
        }
        cntv.push(idx - tmp);
        tmp = idx;
        loop {
            if idx >= l || cv[idx as usize] != '>' {
                break;
            }
            idx += 1;
        }
        cntv.push(idx - tmp);
        tmp = idx;
        if idx >= l {
            break;
        }
    }

    let mut ans: u64 = 0;
    for i in 0..cntv.len() / 2 {
        let j = 2 * i;
        let k = j + 1;
        let n = min(cntv[j], cntv[k]);
        let m = max(cntv[j], cntv[k]);
        if n > 0 {
            ans += n * (n - 1) / 2;
        }
        ans += m * (m + 1) / 2;
    }

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