import collections
S = list(input())
ans = len(S)
deep = 0
D = collections.defaultdict(collections.deque)
NG = collections.defaultdict(int)
NG[0]=1
for s in S:
    if s == '<':
        deep+=1
        D[deep] = collections.deque()
        D[deep].append(s)
    if s == '=':
        D[deep].append(s)
    if s == '>':
        if len(D[deep])<=1:
            NG[deep]=1
        D[deep].append(s)
        if NG[deep]==0:
            ans-=len(D[deep])
            deep-=1
print(ans)