S = input()
cnt = 0
for i in range(len(S)):
    j = len(S) - i - 1
    if S[i] != S[j] and i < j:
        cnt += 1
print(cnt)

65b938f27bc34a25ba6529d48e2fb0c7f11d257d
<mask token>

<mask token>
for i in range(len(S)):
    j = len(S) - i - 1
    if S[i] != S[j] and i < j:
        cnt += 1
print(cnt)

S = input()
cnt = 0
for i in range(len(S)):
    j = len(S) - i - 1
    if S[i] != S[j] and i < j:
        cnt += 1
print(cnt)
