s = input()
ans = []
p = 0
for i in range(len(s)):
    
    if s[i] == "<":
        ans.append(1)
    elif len(ans) == 0:
        p += 1
    elif s[i] == ">":
        if ans[-1] == 1:
            p += sum(ans) + 1
            ans = []
        else: ans.pop()
    else:
        ans[-1] += 1
print(p + sum(ans))