import sys
input = sys.stdin.readline
S = input().strip()
dp = []
for s in S:
    if s=="<":
        dp.append(1)
    elif s=="=":
        if dp and (dp[-1]==1 or dp[-1]==2):
            dp.append(2)
        else:
            dp.append(0)
    else:
        if dp and dp[-1]==2:
            dp.append(3)
            while dp and dp[-1]>1:
                dp.pop()
            dp.pop()
        else:
            dp.append(0)
print(len(dp))