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 Python (3.4.3) (judge verdict: Wrong Answer)

def calcsum(n):
    return n * (n + 1) // 2

s = str(input())
n = len(s) + 1
arrk = []
arrg = []
tmp = s[0]
cnt = 1
for i in range(1, n-1):
    if s[i] == tmp:
        cnt += 1
    elif s[i] != tmp:
        if tmp == '<':
            arrk.append(cnt)
        else:
            arrg.append(cnt)
        cnt = 1
        tmp = s[i]
if tmp == '<':
    arrk.append(cnt)
else:
    arrg.append(cnt)
#print(arrk, arrg)
ans = 0
for i in range(len(arrk)):
    #print(calcsum(arrk[i]-1))
    ans += calcsum(arrk[i]-1)
for i in range(len(arrg)):
    #print(calcsum(arrg[i]-1))
    ans += calcsum(arrg[i]-1)
#print('ans',ans)
if s[0] == '<':
    for i in range(len(arrg)):
        #print('a', max(arrg[i], arrk[i]))
        ans += max(arrg[i], arrk[i])
    if len(arrg) > len(arrk):
        ans += arrg[len(arrg)-1]
    elif len(arrk) > len(arrg):
        ans += arrk[len(arrk)-1]
elif s[0] == '>':
    ans += arrg[0]
    for i in range(len(arrk)-1):
        #print('a', max(arrg[i+1], arrk[i]))
        ans += max(arrg[i+1], arrk[i])
    if len(arrg) > len(arrk):
        ans += arrg[len(arrg)-1]
    elif len(arrk) > len(arrg):
        ans += arrk[len(arrk)-1]
    else:
        if s[n-2] == '<':
            ans += arrk[len(arrk)-1]
print(ans)