import sys, math
sys.setrecursionlimit(10**7)
from itertools import *
from heapq import heapify, heappush, heappop
from collections import deque, defaultdict, Counter
from bisect import bisect_left, bisect_right
from copy import copy, deepcopy
# from sortedcontainers import SortedSet, SortedList, SortedDict
INF, LINF, ipt = float('inf'), 1 << 60, sys.stdin.readline
iin, mii = lambda: int(ipt()), lambda: map(int, ipt().split())
lmi = lambda: list(map(int, ipt().split()))

S = input()
N = len(S)

st = deque()
ans = N

for i in range(N):
    if S[i] == "<":
        st.append(1)
    elif S[i] == "=":
        st.append(0)
    else:
        cnt = 0
        while st and st[-1] == 0:
            cnt += 1
            st.pop()
        if cnt == 0:
            st.append(-1)
            continue

        if st and st[-1] == 1:
            ans -= cnt + 2
            st.pop()
        else:
            st.append(-1)

print(ans)