Problem:
 Score : 200 points    Problem Statement  Takahashi loves palindromes. Non-palindromic strings are unacceptable to him. Each time he hugs a string, he can change one of its characters to any character of his choice.  Given is a string S . Find the minimum number of hugs needed to make S palindromic.      Constraints   S is a string consisting of lowercase English letters.  The length of S is between 1 and 100 (inclusive).         Input  Input is given from Standard Input in the following format:  S       Output  Print the minimum number of hugs needed to make S palindromic.        Sample Input 1 redcoder      Sample Output 1 1  For example, we can change the fourth character to o and get a palindrome redooder .       Sample Input 2 vvvvvv      Sample Output 2 0  We might need no hugs at all.       Sample Input 3 abcdabc      Sample Output 3 2

Solution (Python):
s = input()
i, j, ans = 0, len(s) - 1, 0
while i < j:
    if s[i] != s[j]:
        ans += 1
    i += 1
    j -= 1
print(ans)

Solution (Python):
s = input()
cnt = 0
for i in range(len(s) // 2):
    if s[i] != s[-i - 1]:
        cnt += 1
print(cnt)

Solution (Python):
s = list(str(input()))
re_s = s[::-1]

ans = 0
for i in range(len(s)):
    if s[i] != re_s[i]:
        ans += 1
print(ans//2)

Solution (Python):
S = input()

ans = 0
for i in range(len(S)//2):
    if S[i] != S[-i-1]:
        ans += 1
print(ans)

Solution (Python):
s = input()
sp = s[::-1]
diff = [1 for i in range(len(s)) if s[i] != sp[i]]
print(sum(diff)//2)

Solution (Python):
import sys
input = sys.stdin.readline
sys.setrecursionlimit(10 ** 7)

S = input().strip()

ans = 0
for i in range(len(S)//2):
    if S[i] != S[-i-1]:
        ans += 1

print(ans)

Solution (Python):
S = list(str(input()))
N = len(S)
count = 0

for i in range(N//2):
    if S[i] != S[-i-1]:
        count += 1

print(count)

Solution (Python):
S = input()
N = len(S)

ans = 0
for i in range(N // 2):
    ans += S[i] != S[-1-i]

print(ans)

Solution (Python):
s = input()
cnt = 0
for i in range(int(len(s)/2)):
    if s[i] == s[int(len(s))-1-i]:
        pass
    else:
        cnt += 1
print(cnt)

Solution (Python):
s=input()
count=0
for i in range(len(s)//2):
    if s[i]!=s[-i-1]:
        count+=1
print(count)

Solution (Python):
s=input()
ans=chk=0
for i in range(len(s)//2):
    if s[i]!=s[-i-1]:
        ans+=1
print(ans)

Solution (Python):
Ss = input()

N = len(Ss)

ans = 0
for i in range(N//2):
    if Ss[i] != Ss[N-1-i]:
        ans += 1

print(ans)

Solution (Python):
S = input()
cnt = 0
for i in range(len(S) // 2):
    if S[i] != S[-i - 1]:
        cnt += 1

print(cnt)

Solution (Python):
S = input()
T = S[::-1]
ans = 0
for i in range(len(S) // 2):
    if S[i] != T[i]:
        ans += 1
print(ans)

Solution (Python):
s = raw_input()
c = 0
for i in xrange(len(s)):
    j = len(s) - 1 - i
    if i < j and s[i] != s[j]:
        c += 1
print c

Solution (Python):
S = list(input())
SS = S[::-1]
cnt =0
for i in range(len(S)):
    if S[i] != SS[i]:
        cnt += 1
print(cnt//2)

Solution (Python):
string = list(input())

res = 0

for i in range(len(string) // 2):
    if string[i] != string[-i-1]:
        res += 1

print(res)

Solution (Python):
s = input()

n = len(s)
count = 0
for i in range(n // 2):
    if s[i] != s[n-1-i]:
        count += 1

print(count)

Solution (Python):
s = input()
n = len(s)
c = 0
for i in range(n//2+(1 if n%2==1 else 0)):
    if s[i]!=s[-(i+1)]:
        c+=1

print(c)

Solution (Python):
s = input()

leng = len(s)

trid = leng//2

cnt = 0

for i in range(trid):
    if s[i] == s[-i-1]:
        continue
    else:
        cnt += 1
        
print(cnt)

Solution (Python):
S1 = input()
S2 = S1[::-1]
ans = 0
for i in range(len(S1)//2):
    if S1[i] != S2[i]:
        ans+=1
print(ans)

Solution (Python):
s = input()
N=len(s)
sl = s[:N//2]
sr = s[-N//2:][::-1]

ans = 0
for i,j in zip(sl, sr):
	if i!=j:
		ans += 1
print(ans)

Solution (Python):
s = input()
cnt = 0
for i in range(len(s)//2):
    if s[i]!=s[len(s)-1-i]:
        cnt+=1
print(cnt)

Solution (Python):
s = input()

cnt = 0
for i in range(len(s)//2):
	if s[i] != s[len(s)-1-i]:
		cnt += 1
print(cnt)

Solution (Python):
def main():
    S = input()
    a, b = 0, len(S) - 1
    r = 0
    while a < b:
        if S[a] != S[b]:
            r += 1
        a, b = a + 1, b - 1
    print(r)

main()

Solution (Python):
def two_int():
    N, K = map(int, input().split())
    return N,K

def one_int():
    return int(input())

def one_str():
    return input()

def many_int():
    return list(map(int, input().split()))

S=one_str()

half = len(S)//2

count=0
for h,t in zip(S[:half], S[half:][::-1]):
    if h!=t:
        count+=1
print(count)

Solution (Python):
S = input()
N = len(S)

ans = 0
for i in range(N//2):
    if S[i]!=S[-1-i]: ans += 1
print(ans)

Solution (Python):

import sys
sys.setrecursionlimit(200000)
input = sys.stdin.readline
def ii(): return int(input())
def mi(): return map(int, input().rstrip().split())
def lmi(): return list(map(int, input().rstrip().split()))
def fi(): return float(input())
def mfi(): return map(float, input().rstrip().split())
def lmfi(): return list(map(float, input().rstrip().split()))
def li(): return list(input().rstrip())
def debug(*args, sep=" ", end="\n"): print("debug:", *args, file=sys.stderr, sep=sep, end=end) if not __debug__ else None
def exit(*arg): print(*arg); sys.exit()



def main():
    S = input().rstrip()
    cnt = 0
    for i in range(len(S)):
        if S[i] != S[-i - 1]:
            cnt += 1
    print(cnt // 2)
    return


if __name__ == '__main__':
    main()

Solution (Python):
S = input()
N = len(S)
ans = 0
for i in range(N//2):
    if S[i] != S[N-1-i]:
        ans += 1
print(ans)

Solution (Python):
s = input()
ans = 0
for i in range(len(s) // 2):
    if s[i] != s[-(i + 1)]:
        ans += 1
print(ans)

Solution (Python):
import sys
input = sys.stdin.readline
s = input().strip()
ans = 0
for i in range(len(s)//2):
    if s[i] != s[-1-i]:
        ans += 1
print(ans)

Solution (Python):
s=input()
n=len(s)
n_0=n//2
ans=0
for i in range(n_0):
    if s[i]!=s[n-1-i]:
        ans+=1
print(ans)

Solution (Python):
s = input()
cnt = 0
n = len(s)
for i in range(n//2):
    if s[i] != s[-i - 1]:
        cnt += 1
print(cnt)

Solution (Python):
S = list(input())
N = len(S)

ans = 0
for i in range(N // 2):
    if S[i] != S[N - 1 - i]: ans += 1

print(ans)

Solution (Python):






S = input()





count = 0
for i in range(len(S) // 2):
    if S[i] != S[-i-1]:
        count += 1
print(count)

Solution (Python):
s = input()
ans = 0
for i in range(len(s) // 2):
    if s[i] != s[len(s) - 1 - i]:
        ans += 1
print(ans)

Solution (Python):
S = input()
N = len(S)
cnt = 0
for i in range(N//2):
    if S[i] != S[N - i - 1]:
        cnt += 1
print(cnt)

Solution (Python):
import sys

sys.setrecursionlimit(10 ** 6)
int1 = lambda x: int(x) - 1
p2D = lambda x: print(*x, sep="\n")
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]

def main():
    s=input()
    ans=0
    for c1,c2 in zip(s,s[::-1]):
        if c1!=c2:ans+=1
    print(ans//2)
main()

Solution (Python):
s = input()
ans = 0

for i in range(len(s)//2):
    if s[i] != s[len(s)-1-i]:
        ans += 1
        
print(ans)

Solution (Python):
s = input()
n = len(s)
n = n // 2

ans = 0
for i in range(n):
    if s[i] != s[-i-1]:
        ans += 1

print(ans)

Solution (Python):
s=input()
n=len(s)
sm=0 
for i in range(n//2):
    sm+=(s[i]!=s[n-i-1])
print(sm)

Solution (Python):
s = input()
count = 0
for i in range(len(s)//2):
    if s[i] != s[-i-1]:
        count += 1
print(count)

Solution (Python):
s=input()
length = len(s)//2

s1 = s[:length]
if len(s)%2==0:
    s2 = s[length:]
else:
    s2 = s[length+1:]
s2 = s2[::-1]

ans = 0
for a,b in zip(s1,s2):
    if a!=b:
        ans+=1
print(ans)

Solution (Python):
import sys
import math
MAX_INT = int(10e15)
MIN_INT = -MAX_INT
mod = 1000000007
sys.setrecursionlimit(1000000)
def IL(): return list(map(int,input().split()))
def SL(): return input().split()
def I(): return int(sys.stdin.readline())
def S(): return input()

s = S()
N = len(s)
n = N//2

ans = 0
for i in range(n):
  if s[i] != s[N-i-1]:
    ans += 1
print(ans)

Solution (Python):
S = input()
n = len(S)
a = 0
for i in range(n//2):
    if S[i] != S[n-1-i]:
        a += 1
print(a)

Solution (Python):
S=input()
ans = 0
for i in range(len(S)//2):
  if S[i] != S[-i-1]: ans += 1
print(ans)

Solution (Python):
S = input()
ans = 0
for i in range(len(S)):
    if S[i] != S[::-1][i]:
        ans += 1
print(ans // 2)

Solution (Python):
s = input()
n = len(s)
hn = n // 2
res = 0
for i in range(hn):
    if s[i] != s[n - 1 - i]:
        res += 1
print(res)

Solution (Python):
S=input()
l=len(S)
a=0
for i in range(l):
    if S[i]!=S[-i-1]:
        a+=1
print(a//2)

Solution (Python):
S = input()
cnt = 0
for i in range(len(S)//2):
    if S[i] != S[-i-1]:
        cnt += 1
print(cnt)

Solution (Python):
import math

def makelist(n, m):
    return [[0 for _ in range(m)] for _ in range(n)]






S = input()
ans = 0
for i in range(len(S)//2):
    if S[i] != S[-(i+1)]:
        ans += 1
print(ans)

Solution (Python):
s = input()
len_s = len(s)
cnt = 0
for i in range(len_s // 2):
    if s[i] != s[-i-1]:
        cnt += 1
print(cnt)

Solution (Python):
s=input()
sr=s[::-1]
ans=0
for i in range(len(s)//2):
    if s[i]!=sr[i]:
        ans+=1
print(ans)

Solution (Python):
S=input()
T=S[::-1]

ans=0
for i in range(len(S)):
  if S[i]!=T[i]:
    ans+=1
print(ans//2)

Solution (Python):
import sys
readline = sys.stdin.readline
S = list(map(ord, readline().strip()))

cnt = 0
for s, si in zip(S, S[::-1]):
    if s != si:
        cnt += 1
print(cnt//2)

Solution (Python):
s = input()
n = len(s)
print(sum(1 for i in range(n // 2) if s[i] != s[n - 1 - i]))

Solution (Python):
s = input()
cnt = 0
for i in range(len(s) // 2):
    if s[i] != s[-1-i]:
        cnt += 1
print(cnt)

Solution (Python):



def ri():
    return int(input())

def rl():
    return list(input().split())

def rli():
    return list(map(int, input().split()))

def main():
    s = input()
    ans = 0
    for i in range(len(s)//2):
        if s[i] != s[len(s)-1-i]:
            ans += 1
    print(ans)


if __name__ == '__main__':
    main()

Solution (Python):
S = input()
n = len(S)
u = 0
for i in range(n // 2):
  if S[i] != S[n - 1 - i]:
    u += 1
print(u)

Solution (Python):
s = input()
n = len(s)
ans = 0
for i in range(n//2):
	if s[i] != s[n-i-1]:
		ans += 1
print(ans)

Solution (Python):
s=list(input())
n=len(s)
k=n//2
a=0
for i in range(k):
    if s[i]!=s[n-i-1]:
        a+=1
print(a)

Solution (Python):
S = input()
cnt = 0

for i in range(len(S)//2):
    if S[i]!=S[len(S)-1-i]:
        cnt += 1

print(cnt)

Solution (Python):
S = input()
N = len(S)//2
ans = 0
for i in range(N):
    if S[i] != S[-i-1]:
        ans += 1
print(ans)

Solution (Python):
S = input()

N = len(S)//2

ans = 0
for a,b in zip(S[:N],S[-1:N-1:-1]):
    if a != b:
        ans += 1
print(ans)

Solution (Python):
S = input()

N = len(S)

ret = 0
for i in range(N // 2) :
    if S[i] != S[N-1-i] :
        ret += 1
        
print(ret)

Solution (Python):
s=input()
n=len(s)
import math
m=math.ceil(n/2)
ans=0
for i in range(m):
    if s[i]!=s[n-1-i]:
        ans+=1
print(ans)

Solution (Python):
s = input()
ans = 0
for i in range(len(s)//2):
  if s[i]!=s[-i-1]:
    ans+=1
print(ans)

Solution (Python):
s=input()
turn=len(s)//2
answer=0

for i in range(turn):
    
    if s[i]!=s[-i-1]:
        answer+=1

print(answer)

Solution (Python):
s = input()
cnt = 0
for i in range(len(s) // 2):
  if s[i] != s[-i-1]:
    cnt += 1
print(cnt)

Solution (Python):
S = input()

ans = 0
for i in range(len(S) // 2):
    ans += int(S[i] != S[-i - 1])
    
print(ans)

Solution (Python):
S = input()
ans = 0
for i in range(len(S) // 2):
    if S[i] != S[-(i+1)]:
        ans += 1
print(ans)

Solution (Python):
S = input()

n = len(S)
print(sum([a != b for a, b in zip(S[:n//2], S[::-1][:n//2])]))

Solution (Python):
s = input()

ans = 0
for i in range(len(s) // 2):
    if s[i] != s[len(s) - i - 1]:
        ans += 1
print(ans)

Solution (Python):

import bisect
import heapq
import math
import random
import sys
from collections import Counter, defaultdict, deque
from decimal import ROUND_CEILING, ROUND_HALF_UP, Decimal
from functools import lru_cache, reduce
from itertools import combinations, combinations_with_replacement, product, permutations
from operator import add, mul, sub

sys.setrecursionlimit(100000)
input = sys.stdin.readline
INF = 2**62-1

def read_int():
    return int(input())


def read_int_n():
    return list(map(int, input().split()))


def read_float():
    return float(input())


def read_float_n():
    return list(map(float, input().split()))


def read_str():
    return input().strip()


def read_str_n():
    return list(map(str, input().split()))


def error_print(*args):
    print(*args, file=sys.stderr)


def mt(f):
    import time

    def wrap(*args, **kwargs):
        s = time.time()
        ret = f(*args, **kwargs)
        e = time.time()

        error_print(e - s, 'sec')
        return ret

    return wrap


@mt
def slv(S):
    ans = 0
    for i in range(len(S)//2):
        if S[i] != S[len(S)-i-1]:
            ans += 1
    return ans


def main():
    S = read_str()
    print(slv(S))


if __name__ == '__main__':
    main()

Solution (Python):


s=input()

i=0
j=len(s)-1
c=0
while(i<j):
	if(s[i]!=s[j]):
		c+=1
	i+=1
	j-=1

print(c)

Solution (Python):
import sys
sys.setrecursionlimit(1000000000)
from itertools import count
from functools import lru_cache
from collections import defaultdict
ii = lambda: int(input())
mis = lambda: map(int, input().split())
lmis = lambda: list(mis())
INF = float('inf')
def meg(f, ok, ng):
    while abs(ok-ng)>1:
        mid = (ok+ng)//2
        if f(mid):
            ok=mid
        else:
            ng=mid
    return ok


def main():
    S = input()
    print(sum(S[i]!=S[-(i+1)] for i in range(len(S)//2)))

main()

Solution (Python):
S =list(input())
ans = 0
for s, r in zip(S, S[::-1]):
  if s != r:
    ans += 1
print(ans//2)

Solution (Python):
S = input()
ans = 0
for s, t in zip(S, S[::-1]):
    if s != t: ans += 1
print(ans // 2)

Solution (Python):
s=input()
p=s[::-1]
cnt=0
for i in range(len(s)):
	if s[i]!=p[i]:
		cnt+=1
print(cnt//2)

Solution (Python):
s = input()

ans = sum(1 for i in range(len(s)//2) if s[i]!=s[-i-1])

print(ans)

Solution (Python):
ans = 0
s = list(input())
t = s[::-1]
for i in range(len(s)//2):
  if s[i] != t[i]:
    ans += 1

print(ans)

Solution (Python):
S = list(input())

N = len(S)
count = 0
for i in range(N // 2):
    if S[i] != S[N - 1 - i]:
        count += 1

print (count)

Solution (Python):
S = input()
cnt = 0
for i in range(len(S)//2):
    if S[i] != S[-(i+1)]:
        cnt += 1
print(cnt)

Solution (Python):
S = input()
_S = S[::-1]
res = 0
for x in range(len(S)):
    if S[x] != _S[x]:
        res += 1
print(res//2)

Solution (Python):
s = input()
hits = 0
leng = 0
for k in range(len(s)//2):
    hits += s[k] == s[-k - 1]
    leng += 1
print(leng - hits)

Solution (Python):
def p_b():
    s = input()
    length = len(s) // 2
    ans = 0
    for i in range(length):
        if s[i] != s[~i]:
            ans += 1
    print(ans)
    
p_b()

Solution (Python):

import sys, math, itertools, heapq, collections, bisect, string
input = lambda: sys.stdin.buffer.readline().rstrip().decode('utf-8')
sys.setrecursionlimit(10**7)
inf = float('inf')
mod = 10**9+7
ans = inf ;count = 0 ;pro = 1

s = input()
t = s[::-1]
for i in range(len(s)):
    if s[i] != t[i]:
        count += 1
print(count//2)

Solution (Python):
s = input()
lens = len(s)
change = 0
for i in range(lens//2):
    if s[i] != s[lens - i -1]: change += 1
print(change)

Solution (Python):
S=input()
print(sum([1 if S[i]!=S[-i-1] else 0 for i in range(len(S)//2)]))

Solution (Python):
S = input()

print(sum(a!=b for a,b in zip(S, S[::-1]))//2)

Solution (Python):
S = input()
ans = 0
for i in range(len(S) // 2):
    if S[i] != S[-(i + 1)]:
        ans += 1

print(ans)

Solution (Python):
st = input()
i = 0
j = len(st)-1
c = 0
while i<j:
    if st[i]!=st[j]:
        c += 1
    i += 1
    j -= 1
print(c)

Solution (Python):
def main():
    s=input()
    cnt=0
    for i in range(len(s)//2):
        if s[i]!=s[len(s)-i-1]:
            cnt+=1
    print(cnt)
main()

Solution (Python):
S = input()
ans = 0
for k in range(len(S)//2):
    if S[k] != S[-k-1]:
        ans += 1
print(ans)

Solution (Python):
S = input()

ans = 0
for i in range(len(S)//2):
    if S[i] != S[len(S)-i-1]:
        ans+=1
print(ans)

Solution (Python):
s=input()
ss=s[::-1]
x=0
for i in range(len(s)):
  if s[i]!=ss[i]:
    x+=1
print(x//2)

Solution (Python):
s=input()
n=len(s)
cnt=0
for i in range(n//2):
    a=s[i]
    b=s[n-1-i]
    if a != b:
        cnt+=1
print(cnt)

Solution (Python):
S = input()
n = len(S)
ans = 0
for i in range(n//2):
    if S[i] != S[-i-1]:
        ans+=1
print(ans)

Solution (Python):
S = input()
N = len(S)
ans = 0
for i in range(N//2):
    if S[i]!=S[-(i+1)]: ans+=1
print(ans)

Solution (Python):
s = str(input())
n = len(s)
m = n//2
ans = 0
for i in range(m):
    if s[i] !=s[n-1-i]:
        ans +=1
print(ans)

Solution (Python):

S = input()
ans = 0

for i in range(len(S) // 2):

    if S[i] != S[-1-i]:
        ans += 1

print (ans)

Solution (Python):
S = list(map(str, input()))
res = 0
for i in range(len(S) // 2):
	if S[i] != S[- 1 - i]:
		res += 1
print(res)

Solution (Python):
import sys
sys.setrecursionlimit(2147483647)
INF=float("inf")
MOD=10**9+7
input=lambda:sys.stdin.readline().rstrip()
def resolve():
    S=input()
    n=len(S)
    pre=S[:n//2]
    suf=S[n-n//2::]
    suf=suf[::-1]
    ans=0
    for p,s in zip(pre,suf):
        ans+=(p!=s)
    print(ans)
resolve()

Solution (Python):
s = list(input())
n = len(s)

ans = 0
for i in range(n):
    if s[i] != s[-1-i]:
        s[i] = s[-1-i]
        ans += 1
print(ans)

Solution (Python):

import sys
sys.setrecursionlimit(10**6)
input = sys.stdin.readline

s = input().rstrip()
cnt = 0
for s1, s2 in zip(s, s[::-1]):
    if s1 != s2:
        cnt += 1
print(cnt // 2)

Solution (Python):
s = input()
n = len(s)

left = 0
right = n - 1
ret = 0
while left <= right:
    if s[left] != s[right]:
        ret += 1
    left += 1
    right -= 1
print(ret)

Solution (Python):
S = input()
N = len(S)
ans = 0
for i in range(N//2):
    if S[i]!=S[-1-i]:
        ans += 1
print(ans)

Solution (Python):
s = input()
s_ = s[::-1]
ans = 0
for i in range(len(s)):
    if s[i] != s_[i]:
        ans += 1
print(ans // 2)

Solution (Python):
s=input()
a=0
for i in range(len(s)//2):
    if s[i]!=s[-i-1]:
        a+=1
print(a)

Solution (Python):
def main():

    S = input()
    n = len(S)
    ans = 0
    for i in range(n//2):
        if S[i] != S[n-1-i]:
            ans += 1
    return ans

if __name__ == '__main__':
    print(main())

Solution (Python):
import sys
sys.setrecursionlimit(10**9)
INF=10**18
def input():
    return sys.stdin.readline().rstrip()

def main():
    S=list(input())
    N=len(S)
    ans=0
    for i in range(N//2):
        ans+=1 if S[i]!=S[N-1-i] else 0
    print(ans)

if __name__ == '__main__':
    main()

Solution (Python):
s=input()
cnt=0
for i in range(len(s)//2):
    if s[i]!=s[-(i+1)]:cnt +=1
print(cnt)

Solution (Python):



def main():
    import sys
    input = sys.stdin.readline
    sys.setrecursionlimit(10**6)

    
    s = input()[:-1]
    ans = 0
    for i in range(len(s) // 2):
        if s[i] != s[-i-1]:
            
            ans += 1
    print(ans)


if __name__ == '__main__':
    main()

Solution (Python):
s=list(input())
n=len(s)
s1=s[:n//2]
s2=s[n//2:]
s2.reverse()
ans=0
for i in range(n//2):
    if s1[i]!=s2[i]:
        ans+=1
print(ans)

Solution (Python):
S = list(input())
i,j = 0, len(S) - 1
ans = 0
while i < j:
  if S[i] != S[j]:
    ans += 1
  i += 1
  j -= 1

print(ans)

Solution (Python):

ans = 0
S = input()
length = len(S)
for i in range(length//2):
    if S[i] != S[length-i-1]: ans += 1
print(ans)

Solution (Python):
s = input()

ans = 0
for i, j in zip(s, s[::-1]):
    if i != j:
        ans += 1

print(ans//2)

Solution (Python):
import sys
input = sys.stdin.readline

S=input().strip()
ANS=0

for i in range(len(S)//2):
    if S[i]==S[-i-1]:
        continue
    else:
        ANS+=1
print(ANS)

Solution (Python):
s = list(input())

ans = 0
L = 0
R = len(s) - 1

while L < R:
    if s[L] != s[R]:
        ans += 1
    L += 1
    R -= 1

print(ans)

Solution (Python):
s = input()
n = len(s)
cnt = 0
if n % 2 == 0:
    for i in range(n // 2):
        if s[i] != s[n - 1 - i]:
            cnt += 1
else:
    for i in range(n // 2):
        if s[i] != s[n - 1 - i]:
            cnt += 1
print(cnt)

Solution (Python):
S = raw_input()
print sum(S[i]!=S[-i-1] for i in range(len(S)/2))

Solution (Python):
s = input()
n = len(s)
print(sum(1 for i in range(n // 2) if s[i] != s[n - 1 - i]))

Solution (Python):

s = input()
ans = 0
for i in range(len(s) // 2):
    if s[i] != s[-1 - i]:
        ans += 1
print(ans)

Solution (Python):
S = input()
N = len(S)

ans = 0
for i in range(N // 2):
  if S[i] != S[N - 1 - i]:
    ans += 1
print(ans)

Solution (Python):











import sys
sys.setrecursionlimit(10**6)
input=sys.stdin.readline
from math import floor,ceil,sqrt,factorial,log 
from heapq import heappop, heappush, heappushpop
from collections import Counter,defaultdict,deque
from itertools import accumulate,permutations,combinations,product,combinations_with_replacement
from bisect import bisect_left,bisect_right
from copy import deepcopy
inf=float('inf')
mod = 10**9+7
def pprint(*A): 
    for a in A:     print(*a,sep='\n')
def INT_(n): return int(n)-1
def MI(): return map(int,input().split())
def MF(): return map(float, input().split())
def MI_(): return map(INT_,input().split())
def LI(): return list(MI())
def LI_(): return [int(x) - 1 for x in input().split()]
def LF(): return list(MF())
def LIN(n:int): return [I() for _ in range(n)]
def LLIN(n: int): return [LI() for _ in range(n)]
def LLIN_(n: int): return [LI_() for _ in range(n)]
def LLI(): return [list(map(int, l.split() )) for l in input()]
def I(): return int(input())
def F(): return float(input())
def ST(): return input().replace('\n', '')
def main():
    S=ST()
    ans = 0
    for i,s in enumerate(S):
        if s!=S[-i-1]:
            ans += 1
    print(ans//2)
if __name__ == '__main__':
    main()

Solution (Python):
S = list(input())

cnt = 0
for i in range(len(S) // 2):
  if S[i] != S[-1 - i]:
    cnt += 1

print(cnt)

Solution (Python):
s = input()
res = 0
for i in range(len(s) // 2):
  res += (s[i] != s[len(s) - i - 1])
print(res)

Solution (Python):
s = input()
count = 0
for c, d in zip(s, s[::-1]):
    if c != d:
        count += 1
print(count // 2)

Solution (Python):
import bisect
from math import ceil, floor, sqrt

S = input()
count = 0
for i in range(len(S) // 2):
    if S[i] != S[len(S) - i - 1]:
        count += 1
print(count)

Solution (Python):
s = input()
ans = 0
for i in range(len(s) // 2):
    if s[i] != s[len(s) - i - 1]:
        ans += 1
print(ans)

Solution (Python):
import sys
import math
from collections import defaultdict

sys.setrecursionlimit(10**7)
def input():
    return sys.stdin.readline()[:-1]

mod = 10**9 + 7

def I(): return int(input())
def II(): return map(int, input().split())
def III(): return list(map(int, input().split()))
def Line(N,num):
    if N<=0:
        return [[]]*num
    elif num==1:
        return [I() for _ in range(N)]
    else:
        read_all = [tuple(II()) for _ in range(N)]
        return map(list, zip(*read_all))



S = str(input())
n = len(S)
count = 0
for i in range(n//2):
    if S[i]!=S[n-1-i]:
        count += 1
print(count)

Solution (Python):
import sys

input = sys.stdin.readline

ri = lambda: int(input())
rs = lambda: input().rstrip()
ril = lambda: list(map(int, input().split()))
rsl = lambda: input().rstrip().split()
ris = lambda n: [ri() for _ in range(n)]
rss = lambda n: [rs() for _ in range(n)]
rils = lambda n: [ril() for _ in range(n)]
rsls = lambda n: [rsl() for _ in range(n)]

s = rs()
count = 0
n = len(s)
t = s[::-1]
for i in range(n // 2):
    if s[i] != t[i]:
        count += 1
print(count)

Solution (Python):
s = input()
count = 0
for i in range(len(s)//2):
    if s[i] != s[-(i+1)]:
        count += 1
print(count)

Solution (Python):
s = input()

l = len(s)
ans = 0
for i in range(l // 2):
    
    if s[i] != s[l - i - 1]:
        ans += 1
print(ans)

Solution (Python):
s = input()
ans = 0
for i in range(0, len(s)//2):
    if list(s)[i] != list(s)[len(s)-i-1]:
        ans += 1
print(ans)

Solution (Python):
S = input()
ans = 0
for i in range(len(S)//2):
    if(S[i] != S[-i-1]):
        ans += 1

print(ans)

Solution (Python):
s = input()
n = len(s)
ans = 0

for i in range(n // 2):
    if s[i] != s[n - i -1]:
        ans += 1

print(ans)

Solution (Python):
S = input()
L = len(S)
k = 0
for i in range(L):
    if S[i] != S[-i-1]:
        k += 1
print(k//2)

Solution (Python):
from collections import Counter,defaultdict,deque
import sys
import bisect
import math
import itertools
import string
import queue
import copy


from itertools import permutations, combinations
from heapq import heappop, heappush

sys.setrecursionlimit(10**8)
mod = 10**9+7
 
def inp(): 
    return int(input())
def inpm(): 
    return map(int,input().split())
def inpl(): 
    return list(map(int, input().split()))
def inpls(): 
    return list(input().split())
def inplm(n): 
    return list(int(input()) for _ in range(n))
def inpll(n): 
    return [list(map(int, input().split())) for _ in range(n)]

def main():
    s=list(input())
    n=len(s)
    ans=0
    for i in range(n//2):
        if s[i]!=s[n-1-i]:
            ans+=1
    print(ans)

if __name__ == "__main__":
    main()

Solution (Python):
s = input()

ans = 0
for i in range(len(s)//2):
    if s[i] != s[-i-1]:
        ans += 1

print(ans)

Solution (Python):
s = str(input())
n = len(s)
r = 0
for i in range(n//2):
    if s[i] == s[-i-1]:
        continue
    else:
        r += 1
print(r)

Solution (Python):
s = input()

ans = 0

for i in range(len(s)//2):
    if s[i] != s[-i-1]:
        ans += 1

print(ans)

Solution (Python):
s = input()
count = 0
for i in range(len(s)//2):
    if s[i] != s[len(s)-1-i]:
        count += 1
print(count)

Solution (Python):
S = input()
cnt = 0

for s, t in zip(S, S[:: -1]):
    if s != t:
        cnt += 1

print(cnt // 2)

Solution (Python):
import bisect
import heapq
import itertools
import math
import operator
import os
import re
import string
import sys
from collections import Counter, deque, defaultdict
from copy import deepcopy
from decimal import Decimal
from fractions import gcd
from functools import lru_cache, reduce
from operator import itemgetter, mul, add, xor

import numpy as np

if os.getenv("LOCAL"):
    sys.stdin = open("_in.txt", "r")

sys.setrecursionlimit(10 ** 9)
INF = float("inf")
IINF = 10 ** 18
MOD = 10 ** 9 + 7


S = sys.stdin.buffer.readline().decode().rstrip()
T = S[::-1]

cnt = 0
for i in range(len(S)):
    cnt += S[i] != T[i]
ans = cnt // 2
print(ans)

Solution (Python):
s=input()
ans=0
for i in range(len(s)//2):
    if s[i]!=s[-(i+1)]:ans+=1
print(ans)

Solution (Python):
s=input()
print(sum(i!=j for i,j in zip(s,s[::-1]))//2)

Solution (Python):
S = input()
T = S[::-1]
a = 0
for s,t in zip(S,T):
    if s!=t:
        a += 1
print(a//2)

Solution (Python):
s=input()
a=0
for i in range(len(s)//2):
    if s[i]!=s[-1-i]:
        a+=1
print(a)

Solution (Python):
import queue
import math
import copy
"""
N = int(input())



A = []
for i in range(N):
	A.append(int(input()))

print(A)

"""

S = input()
ans = 0
for i in range(len(S)//2):
	if S[i] != S[len(S)-1-i]:
		ans += 1
print(ans)

Solution (Python):


s = input()
n=len(s)
ans=0
for i in range(n//2):
    if s[i] != s[n-i-1]:
        ans += 1
print(ans)

Solution (Python):
s = input()
n = len(s)
res = 0
for i in range(n // 2):
    a, b = s[i], s[-1-i]
    if a != b:
        res += 1

print(res)

Solution (Python):
import sys


def solve():
    readline = sys.stdin.buffer.readline
    mod = 10 ** 9 + 7
    s = str(readline().rstrip().decode('utf-8'))
    cnt = 0
    for i in range(len(s)):
        if s[i] != s[-i-1]:
            cnt += 1
    print(cnt // 2)


if __name__ == '__main__':
    solve()

Solution (Python):

from collections import defaultdict,deque
from heapq import heappush, heappop
import sys
import math
import bisect
import random
def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def LS():return [list(x) for x in sys.stdin.readline().split()]
def S():
    res = list(sys.stdin.readline())
    if res[-1] == "\n":
        return res[:-1]
    return res
def IR(n):
    return [I() for i in range(n)]
def LIR(n):
    return [LI() for i in range(n)]
def SR(n):
    return [S() for i in range(n)]
def LSR(n):
    return [LS() for i in range(n)]

sys.setrecursionlimit(1000000)
mod = 1000000007

def solve():
    s = input()
    ans = 0
    for i in range(len(s)>>1):
        ans += (s[i] != s[-1-i])
    print(ans)
    return


if __name__ == "__main__":
    solve()