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)

#![allow(non_snake_case,unused_imports)]
use std::io::Read;
use std::cmp::max;
use std::cmp::min;
use std::str::FromStr;
use std::collections::HashMap;
use std::collections::HashSet;
use std::collections::BinaryHeap;

fn main(){
    let mut buf = String::new();
    std::io::stdin().read_to_string(&mut buf).unwrap();
    let mut iter = buf.split_whitespace();
    let S = iter.next().unwrap().chars().collect::<Vec<_>>();
    //let N = iter.next().unwrap().parse::<usize>().unwrap();
    //let M = iter.next().unwrap().parse::<usize>().unwrap();
    let N = S.len();
    let mut a = (0..N+1).map(|_| -1).collect::<Vec<_>>();
    let mut p = '>';
    for (i,&s) in S.iter().enumerate(){
        if p == '>' && s == '<'{
            a[i] = 0;
        }
        p = s;
    }
    if S[N-1]=='>'{
        a[N] = 0;
    }
    for (i,&s) in S.iter().enumerate(){
        if s == '<' && a[i]!=-1{
            a[i+1] = a[i]+1;
        }
    }
    for i in 0..N{
        let i = N-i-1;
        let s = S[i];
        if s == '>' && a[i+1]!=-1{
            a[i] = max(a[i],a[i+1]+1);
        }
    }
    println!("{}",a.iter().sum::<i64>());
}