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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using static System.Math;
using System.Linq;
using System.Text;
 
class DandA {
    static void Main(string[] args) {
        string s = ReadLineStr();
        int length = s.Length;
        long[] rtnArr = new long[length + 1];
        string wk = "";
        int cnt = 0;
        for (int i = 0;i < length;i++) {
            string chr = s.Substring(i, 1);
            if (wk != chr) {
                if (chr == "<") {
                    for (int j = 0;j < cnt;j++) {
                        rtnArr[i - j] = j;
                    }
                    if (rtnArr[i - (cnt)] < cnt) {
                        rtnArr[i - (cnt)] = cnt;
                    }
                } else {
                    if (cnt ==0) {cnt++;}
                    rtnArr[i] = cnt;
                }
                wk = chr;
                cnt = 1;
            } else {
                if (chr == "<") {
                    rtnArr[i] = cnt;
                }
                cnt++;
            }
        }
        if (cnt != 0) {
            if (wk == "<") {
                rtnArr[length] = cnt;
            } else {
                for (int j = 0;j < cnt;j++) {
                    rtnArr[length - j] = j;
                }
                if (rtnArr[length - cnt] < cnt) {
                    rtnArr[length - cnt] = cnt;
                }
            }
        }
        Console.WriteLine(rtnArr.Sum());
    }
 
    static string alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ";
    static string[] strAry = new string[] {"L", "R", "U", "D"};
    static int[] intArray = new int[10];
    static List<int> intList = new List<int>();
    static Dictionary<string, int> myTable = new Dictionary<string, int>();
    static HashSet<int>[] rtnArrAb = null;
    static HashSet<int>[] rtnArrCd = null;
    static long[,] Combi = new long[2001,2001];
    static long div = 1000000007;
  
    static private string ReadLineStr() {return Console.ReadLine();}
    static private int ReadLineInt() {return int.Parse(Console.ReadLine());}
    static private long ReadLineLong() {return long.Parse(Console.ReadLine());}
    static private double ReadLineDouble() {return double.Parse(Console.ReadLine());}
    static private string[] ReadLineStrArray() {return Console.ReadLine().Trim().Split();}
    static private int[] ReadLineIntArray() {return Console.ReadLine().Trim().Split().Select(a => int.Parse(a)).ToArray();}
    static private long[] ReadLineLongArray() {return Console.ReadLine().Trim().Split().Select(a => long.Parse(a)).ToArray();}
    static private double[] ReadLineDoubleArray() {return Console.ReadLine().Trim().Split().Select(a => double.Parse(a)).ToArray();}
    static private decimal[] ReadLineDecimalArray() {return Console.ReadLine().Trim().Split().Select(a => decimal.Parse(a)).ToArray();}
    static private List<int> ReadLineIntList() {return Console.ReadLine().Trim().Split().Select(a => int.Parse(a)).ToList();}
    static private List<long> ReadLineLongList() {return Console.ReadLine().Trim().Split().Select(a => long.Parse(a)).ToList();}
    static private string[][] ReadMLineStrArray(int arg) { return new int[arg].Select(_ => Console.ReadLine().Split()).ToArray();}
    static private int[][] ReadMLineIntArray(int arg) { return new int[arg].Select(_ => Console.ReadLine().Split().Select(int.Parse).ToArray()).ToArray();}
 
    static private bool IsPrime(int num) {
        if (num < 2) return false;
        if (num == 2) return true;
        else if (num % 2 == 0) return false;
        double sqrtNum = Math.Sqrt(num);
        for (int i = 3; i <= sqrtNum; i += 2) {
            if (num % i == 0) return false;
        }
        return true;
    }
  
    static private string IntToNString(int x, int n) {
        var nstring = "";
        var numbers = new string[] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
        int r = 1;
        int q = x;
        while (q > 0) {
            r = q % n;
            nstring += numbers[r];
            q = q / n;
        }
        return string.Join("",nstring.Reverse());
    }
    static private long Gcd(long m,long n){
        long temp;
        while(m % n != 0) {
            temp = n;
            n = m % n;
            m = temp;
        }
        return n;
    }
 
    static private long Combination(long n,long r){
        if(n < r) {return 0;}
        if(n == r || r == 0) {return 1;}
        else if(Combi[n,r] == 0) {
            Combi[n,r] = (Combination(n-1,r-1)+Combination(n-1,r)) % div;
        }
        return Combi[n,r];
    }
}