S = input()

stack = []
idxL = []
idxR = []
for i in range(len(S)):
    if S[i] == "<":
        stack.append(S[i])
        idxL.append(i)
    elif S[i] == "=":
        stack.append(S[i])
    else:
        if (len(stack) >= 1 and stack[-1] == "=" and
            (len(idxL) >= 1 and len(idxR) == 0 or len(idxL) >= 1 and len(idxR) >= 1 and idxL[-1] > idxR[-1])):
            idxL.pop()
            while stack[-1] == "=":
                stack.pop()
            stack.pop()
        else:
            stack.append(S[i])
            idxR.append(i)

print(len(stack))