S = list(map(str, input()))
stack = []
for i in S:
    if i == "<":
        stack.append(["<", 1])
    elif i == "=":
        if len(stack) >= 1 and stack[-1][0] == "=":
            stack[-1][1] += 1
        else:
            stack.append(["=", 1])
    else:
        stack.append([">", 1])

    if len(stack) >= 3 and stack[-3][0] == "<" and stack[-2][0] == "=" and stack[-1][0] == ">":
        stack.pop()
        stack.pop()
        stack.pop()

ans = 0
for i in stack:
    ans += i[1]

print(ans)