from collections import deque
S=input()
flag = False
dq=deque()
last=deque()
for i in range(len(S)):
    if S[i]=="<":
        last.append("<")
        dq.append("<")
    elif S[i]==">":
        if len(last)>0 and len(dq)>0 and last[-1]=="<" and dq[-1]=="=":
            last.pop()
            p = -1
            while p!="<":
                p=dq.pop()
        else:
            last.append(">")
            dq.append(">")
    else:
        dq.append("=")
    # print(list(dq),list(last))
print(len(dq))