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 Ruby (2.3.3) (judge verdict: Wrong Answer)

S = gets

a_c = S.chars
i = 0
sum = []


#p a_c.length

a_c.each do |th|
  n = 0
  x = 0
  
  if i == 0
    if th == '<'
      sum.push(0)
      i += 1
    else
      while a_c[i] == '>'
        n += 1
      end
      n.times do
        sum.push(n-x)
        x += 1
        i += 1
      end
    end
  else
    if a_c[i] == '<'
      #x = sum[i].to_i + 1
      while a_c[i] == '<'
#        p "'<' #{i}kaime push=#{x}"
        sum.push(x)
        x += 1
        i += 1
      end
    else
      while a_c[i] == '>'
        n += 1
        i += 1
      end
      n.times do
        sum.push(n-x)
        x += 1
      end
    end
  end
end

#p "sum=#{sum}, i=#{i}"

ans = 0

sum.each do |s|
  ans += s
end

p ans