S = list(input()) + ["="]
stack = [">"]
ans = 0
for s in S:
    if s != ">":
        stack.append(s)
    else:
        if stack[-1] == "<":
            ans += len(stack)
            stack = [">"]
        else:
            temp = 0
            while stack[-1] == "=":
                temp += 1
                stack.pop()
            if stack[-1] == "<":
                stack.pop()
            else:
                ans += temp + len(stack)
                stack = [">"]

ans += len(stack) - 2
print(ans)