import sys
mod = 998244353
mod2 = 10**9+7

S = input()
left = []
deled = 0
for i in range(len(S)):
    ni = i-deled
    if S[i] == "<":
        left.append(ni)
    if S[i] == ">":
        if len(left) == 0:continue
        if left[-1] + 1 == ni:
            left = []
            continue
        l = left.pop()
        deled += ni-l+1
print(len(S)-deled)