import re
S = str(input())

if len(S) % 3 == 0 and S[:2 * len(S) // 3] == "<=" * (len(S) // 3) and S[2 * len(S) // 3 + 1:] == ">" * (len(S) // 3):
	print(0)
	exit()

new_S = re.sub("<=+>", "", S)
while new_S != S:
  S = new_S
  new_S = re.sub("<=+>", "", S)

print(len(new_S))