S = input()
rle = []
pc = S[0]
cnt = 1
for c in S[1:]:
    if c == pc:
        cnt += 1
    else:
        rle.append((pc, cnt))
        pc = c
        cnt = 1
rle.append((pc, cnt))
stack = []
for c, cnt in rle:
    if c == '>' and len(stack) >= 2 and stack[-2][0] == '<' and stack[-1][0] == '=':
        _, eq_cnt = stack.pop()
        _, lt_cnt = stack.pop()
        if lt_cnt > 1:
            stack.append(('<', lt_cnt - 1))
    else:
        stack.append((c, cnt))
ans = sum(cnt for _, cnt in stack)
print(ans)