S = str(input())
stack = []
ng = []
for i in range(len(S)):
  if S[i] == "<":
    stack.append(i)
  elif S[i] == ">" and stack:
    ng.append((stack.pop(), i))

new_ng = []
left = -1
right = -1
for i, j in ng:
  if left == right == -1:
    left = i
    right = j
  elif i < left and j > right:
    left = i
    right = j
  else:
    new_ng.append((left, right))
    left = i
    right = j
ans = len(S)
for i, j in new_ng:
  ans -= j - i + 1

print(ans)