s = input()
n = len(s)

stack = []
equal = []
ans = n

for i in range(n):
    c = s[i]
    if c == "<":
        stack.append(i)
    elif c == "=":
        equal.append(i)
    elif c == ">":
        if stack:
            if stack[-1] == (i-1):
                stack = []
                equal = []
            else:
                l = stack.pop()
                cnt = 2
                while equal:
                    if l <= equal[-1] < i:
                        equal.pop()
                        cnt += 1
                    else:
                        break
                ans -= cnt
        else:
            equal = []

print(ans)