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

ans = sum(cnt for _, cnt in stack)
print(ans)