S=list(input())
stack=[[S[0]]]
for s in S[1:]:
    if s=="<":
        stack.append([s])
    elif s=="=":
        if stack[-1][-1]=="<" or stack[-1][-1]=="=":
            stack[-1].append(s)
        else:
            stack.append([s])
    else:
        if stack[-1][0]=="<" and stack[-1][-1]=="=":
            stack.pop()
        else:
            stack.append([s])
ans=[]
for s in stack:
    ans+=s
ans="".join(ans)
print(len(ans))