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 Go (1.6) (judge verdict: Accepted)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}

func getNextUint64(scanner *bufio.Scanner) uint64 {
	i, _ := strconv.ParseUint(getNextString(scanner), 10, 64)
	return i
}

func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}

func main() {
	fp := os.Stdin
	wfp := os.Stdout

	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
		if len(os.Args) > 2 {
			wfp, _ = os.Create(os.Args[2])
		}
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(wfp)

	s := getNextString(scanner)
	n := len(s)
	aa := make([]int, n+1)
	for i := n - 1; i >= 0; i-- {
		if s[i] == '>' {
			aa[i] = aa[i+1] + 1
		}
	}
	for i := 0; i < n; i++ {
		if s[i] == '<' {
			aa[i+1] = maxint(aa[i]+1, aa[i+1])
		}
	}

	var ans int64
	for i := 0; i < n+1; i++ {
		ans += int64(aa[i])
	}
	fmt.Fprintln(writer, ans)
	writer.Flush()
}

func maxint(a int, b int) int {
	if a > b {
		return a
	}
	return b
}