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: Accepted)

S = gets.chomp.chars
ans = 0
l_count = 0
r_v = 0
skip_r_v = nil
S.each do |ch|
  if ch == '<'
    l_count += 1
    r_v = 0
    skip_r_v = nil
    ans += l_count - 1
  else
    if r_v + 1 == skip_r_v
      r_v = skip_r_v + 1
    else
      r_v += 1
    end
    if l_count >= 2
      ans += l_count
      skip_r_v = l_count
      r_v = 0
    else
      ans += r_v
    end
    l_count = 0
  end
end
if S[-1] == '<'
  ans += l_count
end
puts ans

# < > > > < < > < < < < < > > > <
# 0 3 2 1 0 1 2 0 1 2 3 4 5 2 1 0 1

# < < > > > >
# 0 1 4 3 2 1

# > > < < < <
# 2 1 0 1 2 3