Problem:


Score : 200 points

Problem Statement

You are given a string S consisting of lowercase English letters.
Find the lexicographically (alphabetically) smallest lowercase English letter that does not occur in S.
If every lowercase English letter occurs in S, print None instead.

Constraints

1 \leq |S| \leq 10^5 (|S| is the length of string S.)

S consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

S

Output

Print the lexicographically smallest lowercase English letter that does not occur in S.
If every lowercase English letter occurs in S, print None instead.

Sample Input 1

atcoderregularcontest

Sample Output 1

b

The string atcoderregularcontest contains a, but does not contain b.

Sample Input 2

abcdefghijklmnopqrstuvwxyz

Sample Output 2

None

This string contains every lowercase English letter.

Sample Input 3

fajsonlslfepbjtsaayxbymeskptcumtwrmkkinjxnnucagfrg

Sample Output 3

d



Sample input:
atcoderregularcontest


Sample output:
b

Submission status: Wrong Answer

Solution code:
S = input()
dic = {}
for i, c in enumerate(range(ord('a'), ord('z')+1)):
    dic[chr(c)] = 0
for c in S:
    dic[c] += 1
for k, v in dic.items():
    if v == 0:
        print(k)
        exit()
print('None')

Submission status: Wrong Answer

Solution code:
print(set(map(chr,range(97,123)))-set(input())or"None")

Submission status: Wrong Answer

Solution code:
S = input()

S_list = []
for s in S:
    if s not in S_list:
        S_list.append(s)

S_list.sort()

al_list = [chr(i) for i in range(97, 97+26)]

if S_list == ['a']: # ここ特別視してるのは下のループの吐くal_list[len...の部分が動かないから
    print('b')
else:
    check_list = []
    for i in range(len(S_list)):
        if S_list[i] == al_list[i]:
            if len(check_list) == 25:
                print('None')
                break
            else:
                check_list.append(True)
        else:
            print(al_list[len(check_list)])
            break

Submission status: Wrong Answer

Solution code:
S = input()

S_list = []
for s in S:
    if s not in S_list:
        S_list.append(s)

S_list.sort()

al_list = [chr(i) for i in range(97, 97+26)]

check_list = []
for i in range(len(S_list)):
    if S_list[i] == al_list[i]:
        if len(check_list) == 25:
            print('None')
            break
        else:
            check_list.append(True)
    else:
        print(al_list[len(check_list)])
        break

Submission status: Wrong Answer

Solution code:
S = input()

S_list = []
for s in S:
    if s not in S_list:
        S_list.append(s)

S_list.sort()

al_list = [chr(i) for i in range(97, 97+26)]

check_list = []
for i in range(len(S_list)):
    if S_list[i] != al_list[i]:
        print(al_list[i])
        break
    else:
        check_list.append(True)

if len(check_list) == 26:
    print('None')

Submission status: Wrong Answer

Solution code:
S=input()
cnt=0
for i in range(ord('a'), ord('z')+1):
  if chr(i) not in S:
    print(chr(i))
    exit()
  else:
    cnt+=1
if cnt==(ord('z')+1-ord('a')):
  print('NONE')

Submission status: Wrong Answer

Solution code:
s = list(input())

r = "None"
for i in range(ord('a'), ord('z')):
	if (s.count(chr(i)) == 0):
		r  = chr(i)
		break

print (r)

Submission status: Wrong Answer

Solution code:
s = list(input())

r = "None"
for i in range(ord('a'), ord('z')):
	if (chr(i) not in s):
		r  = chr(i)
		break

print (r)

Submission status: Wrong Answer

Solution code:
s=list(input())
s=list(set(s))
s.sort()
t='abcdefghijklmnopqrstuvwxyz'
for i in range(len(s)):
  if len(s)==len(t):
    print('None')
    break
  if s[i]==t[i]:
    continue
  else:
    print(t[i])
    break

Submission status: Wrong Answer

Solution code:
s=list(input())
s=list(set(s))
s.sort()
t='abcdefghijklmnopqrstuvwxyz'
for i in range(len(s)):
  if (i+1)==len(t):
    print('None')
  if s[i]==t[i]:
    continue
  else:
    print(t[i])
    break

Submission status: Wrong Answer

Solution code:
s=list(input())
s=list(set(s))
s.sort()
t='abcdefghijklmnopqrstuvwxyz'
for i in range(len(s)):
  if (i+1)==len(t):
    print('None')
  elif s[i]==t[i]:
    continue
  else:
    print(t[i])
    break

Submission status: Wrong Answer

Solution code:
S = input()

import string

S = list(sorted(S))
t = string.ascii_lowercase

flag = True

for a in t:
    if a in S:
        flag = False
        continue
    else:
        print(a)
        break
        
if flag:
    print("None")

Submission status: Wrong Answer

Solution code:
S = input()
for i in range(ord('a'), ord('z')):
    if chr(i) not in S:
        print(chr(i))
        exit()
print('None')

Submission status: Wrong Answer

Solution code:
from string import*
s =input()
s=sorted(s)
alpha_l =[ascii_lowercase[i] for i in range(25)]
print(s,alpha_l)
n='a'
for x in range(25):
	if alpha_l[x] in s:
		if x ==25:
			n = 'None'
			break
		continue
	else:	
		n = alpha_l[x]
		break
print(n)

Submission status: Wrong Answer

Solution code:
s = input()
for i in range(ord("a"), ord("z")+1):
    if chr(i) not in s:
        print(chr(i))
        break

Submission status: Wrong Answer

Solution code:
import string

al = string.ascii_lowercase

alist = list(al)

S = set(input())

Slist = sorted(S)

for x in alist:
    if x not in Slist:
        break

print("None") if x == "z" else print(x)

Submission status: Wrong Answer

Solution code:
import string

al = string.ascii_lowercase

alist = list(al)

S = set(input())

Slist = sorted(S)

for x in alist:
    if x not in Slist:
        break

print(x)

Submission status: Wrong Answer

Solution code:
import sys
s=input()
A='abcdefghijklmnopqrstuvwxyz'
S=sorted(set(s))
for i in range(len(S)):
  if S[i]!=A[i]:
    print(A[i])
    sys.exit()
print('None')

Submission status: Wrong Answer

Solution code:
import sys
s=input()
A='abcdefghijklmnopqrstuvwxyz'
S=sorted(set(s))
for i in range(len(S)):
  if S[i]!=A[i]:
    print(S[i-1])
    sys.exit()
print('None')

Submission status: Wrong Answer

Solution code:
s=list(input())
t=[ord(si) for si in s]
for i in range(97,124):
  if i==124:
    print('None')
    break
  if not i in t:
    print(chr(i))
    break

Submission status: Wrong Answer

Solution code:
s = input()
sset = set(s)
slist = list(sset)
slist.sort()
char = "abcdefghijklmnopqrstuvwxyz"
flg = False
i= 0

for moji in slist:
  if moji != char[i]:
    print(char[i])
    flg = True
    break
  i = i +1
  
  
if flg == False:
  print("None")

Submission status: Wrong Answer

Solution code:
s=sorted(input())
a=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']

for i in a:
    if i not in s:
        print(i)
        break

Submission status: Wrong Answer

Solution code:
s = input()
for i in range(ord('a'), ord('z')+1):
  if chr(i) in s:
    print(chr(i))
    break
else:
  print('None')

Submission status: Wrong Answer

Solution code:
print(chr(i) for i in range(ord('a'), ord('z')+1) if chr(i) not in input())

Submission status: Wrong Answer

Solution code:
s=list(input())
s=set(s)
alp="abcdefghijklmnopqrstuvwxyz"
def search():
  for a in alp:
    if not a in s:
      print(a)
      return
  print(-1)
  return

search()

Submission status: Wrong Answer

Solution code:
s=list(input())
s=set(s)

alp="abcdefghijklmnopqrstuvwxyz"
if len(s)==26:
  print(-1)
else:
  for a in alp:
    if not a in s:
      print(a)
      break

Submission status: Wrong Answer

Solution code:
alp=[chr(i) for i in range(97, 97+26)]
#文字コードで並び替える
#それぞれ一つずつにする
#print(alp)
s=sorted(set(list(input())))

for i in range(len(s)):
    if s[i]!=alp[i] or (i==len(s)-1 and len(s)!=len(alp)):
        print(alp[i])
        break
    if i==len(s)-1:
        print("None")

Submission status: Wrong Answer

Solution code:
alp=[chr(i) for i in range(97, 97+26)]
#文字コードで並び替える
#それぞれ一つずつにする
#print(alp)
s=sorted(set(list(input())))

for i in range(len(s)):
    if s[i]!=alp[i]:
        print(alp[i])
        break
    if i==len(s)-1:
        print("None")
if len(s)==0:
    print("a")

Submission status: Wrong Answer

Solution code:
s=input()

alp=[chr(i) for i in range(97, 97+26)]
#文字コードで並び替える
s=sorted(set(list(s)))
for i in range(len(s)):
    if s[i]!=alp[i]:
        print(alp[i])
        break
    if i==len(s)-1:
        print("None")

Submission status: Wrong Answer

Solution code:
s=input()
for i in range(ord("a"),ord("z")+1):
  if chr(i) in s:
    print(chr(i))
    break
else:
  print("None")

Submission status: Wrong Answer

Solution code:
S = input()

for i in range(ord('a'), ord('z')):
    if chr(i) not in list(S):
        print(chr(i))
        exit()

print('None')

Submission status: Wrong Answer

Solution code:
#alpha=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
alpha= list("abcdefghijklmnopqrstuvwxyz")

s=input()
s_list=sorted(set(s))
for x in s_list:
    if x not in alpha:
        print(x)
        exit()
    
print("None")

Submission status: Wrong Answer

Solution code:
alpha=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
#alpha= list("abcdefghijklmnopqrstuvwxyz")

s=input()
s_list=sorted(set(s))
for x in s_list:
    if x not in alpha:
        print(x)
        exit()
    
print("None")

Submission status: Wrong Answer

Solution code:
alpha=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']

s=input()
s_list=sorted(set(s))
for x, y in zip(s_list, alpha):
    if x!=y:
        print(y)
        exit()
print("None")

Submission status: Wrong Answer

Solution code:
alpha=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']

s=input()
s_list=sorted(set(s))
print(s_list)
for x, y in zip(s_list, alpha):
    if x!=y:
        print(y)
        exit()
print("None")

Submission status: Wrong Answer

Solution code:
nlist = [None] * 150

stri = input()

for i in range(len(stri)):
    ind = ord(stri[i])
    nlist[ind] = 1

#print(nlist)

for i in range(len(nlist)):
    if nlist[i] == None and i > 96:
        print(str(chr(i)))
        break

Submission status: Wrong Answer

Solution code:
nlist = [None] * 150

stri = input()

for i in range(len(stri)):
    ind = ord(stri[i])
    nlist[ind] = 1

print(nlist)

for i in range(len(nlist)):
    if nlist[i] == None and i > 96:
        print(str(chr(i)))
        break

Submission status: Wrong Answer

Solution code:
ans = set(chr(i) for i in range(97,122)) - set(input().rstrip("\n"))

print((list(sorted(ans))+["None"])[0])

Submission status: Wrong Answer

Solution code:
S = input()
S = sorted(S)
i = 0
while i<len(S)-1:
    if ord(S[i]) == ord(S[i+1]) or ord(S[i]) == ord(S[i+1])-1:
        i += 1
    else:
        print(chr(ord(S[i])+1))
        exit(0)

if S[-1] == "z":
    print("None")
else:
    print(chr(ord(S[i])+1))

Submission status: Wrong Answer

Solution code:
S = input()
S = sorted(S)
i = 0
while i<len(S)-1:
    if ord(S[i]) == ord(S[i+1]) or ord(S[i]) == ord(S[i+1])-1:
        i += 1
    else:
        print(chr(ord(S[i])+1))
        exit(0)

if S[-1] == "z":
    print("None")

Submission status: Wrong Answer

Solution code:
S = input()
alpha = [chr(ord('a') + i) for i in range(26)]
n=0
c=0
while c == 0 and n < 26:
  if not alpha[n] in S:
    c = n
    break
  n+=1
if c == 0:
  print('None')
else:
  print(alpha[n])

Submission status: Wrong Answer

Solution code:
S = input()
alpha = [chr(ord('a') + i) for i in range(26)]
n=0
c=0
while c == 0 and n < 26:
  if alpha[n] in S:
    c = n
  n+=1
if c == 0:
  print('None')
else:
  print(alpha[n])

Submission status: Wrong Answer

Solution code:
s=input()
for c in 'abcdefghijklmnopqrstuvwxyz':
  if not c in s:
    print(c)
    break

Submission status: Wrong Answer

Solution code:
s = input()
t = set()
for i in range(len(s)):
  t.add(s[i])
o = list(t)
o.sort()
u = 'qwertyuiopasdfghjklzxcvbnm'
v = []
for i in range(len(u)):
  v.append(u[i])
v.sort()
now = 0
if len(o) == 26:
  print('None')
else:
  for i in range(26):
    if i >= len(t):
      print('None')
      break
    elif o[i] == v[i]:
      now += 1
    else:
      print(v[now])
      break

Submission status: Wrong Answer

Solution code:
s = input()
t = set()
for i in range(len(s)):
  t.add(s[i])
o = list(t)
o.sort()
u = 'qwertyuiopasdfghjklzxcvbnm'
v = []
for i in range(len(u)):
  v.append(u[i])
v.sort()
now = 0
if len(o) == 26:
  print('None')
else:
  for i in range(len(t)):
    if o[i] == v[i]:
      now += 1
    else:
      print(v[now])
      break

Submission status: Wrong Answer

Solution code:
s = input()
t = set()
for i in range(len(s)):
  t.add(s[i])
o = list(t)
o.sort()
u = 'qwertyuiopasdfghjklzxcvbnm'
v = []
for i in range(len(u)):
  v.append(u[i])
v.sort()
now = 0
for i in range(len(t)):
  if o[i] == v[i]:
    now += 1
  else:
    print(v[now])
    break
else:
  print('None')

Submission status: Wrong Answer

Solution code:
s = input()
ls = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]
c = 0
for i in ls:
  if i in s:
    c += 1
  else:
    print(i)
    break
    
if c >= len(s):
  print("None")

Submission status: Wrong Answer

Solution code:
s = list(input())

s_sorted = sorted(set(s))
alpha_dict = {chr(a):0 for a in range(ord('a'), ord('z')+1)}

def getKeyFromValue(d, val):
    keys = [k for k, v in d.items() if v == val]
    if keys:
        return keys[0]
    else:
        return 'None'

for i in range(len(s_sorted)):
    alpha_dict[s_sorted[i]] += 1

print(getKeyFromValue(alpha_dict, 0))

Submission status: Wrong Answer

Solution code:
s = list(input())

s_sorted = sorted(set(s))
alpha_dict = {chr(a):0 for a in range(ord('a'), ord('z')+1)}
#{'a':0, 'b':0, ..., 'z':0}

def getKeyFromValue(d, val):
    keys = [k for k, v in d.items() if v == val]
    if keys:
        return keys[0]
    else:
        return 'None'

for i in range(len(s_sorted)):
    alpha_dict[s_sorted[i]] += 1

print(getKeyFromValue(alpha_dict, 0))

Submission status: Wrong Answer

Solution code:
s = list(input())

s_sorted = sorted(set(s))
alpha_dict = {chr(a):0 for a in range(ord('a'), ord('z')+1)}
#{'a':0, 'b':0, ..., 'z':0}

def getKeyFromValue(d, val):
    keys = [k for k, v in d.items() if v == val]
    if keys:
        return keys[0]
    return 'None'

for i in range(len(s_sorted)):
    alpha_dict[s_sorted[i]] += 1

print(getKeyFromValue(alpha_dict, 0))

Submission status: Wrong Answer

Solution code:
s = list(input())
s_removed = sorted(set(s))
length = len(s_removed)

for i in range(length):
    alphabet = chr(i + ord('a'))
    if s_removed[i] != alphabet:
        print(alphabet)
        break
    if i == length - 1 :
        print('None')

Submission status: Wrong Answer

Solution code:
if __name__ == '__main__':
    S = input()

    complement_S = list(set([chr(i) for i in range(ord('a'), ord('z'))]) - set(list(S)))

    if len(complement_S) == 0:
        print("None")
    else:
        print(min(complement_S))

Submission status: Wrong Answer

Solution code:
S = input()
str = "abcdefghijklmnopqrstuvwxyz"
l1 = list(str)
l2 = list(S)
l3 = set(l1)-set(l2)
print(l3)

Submission status: Wrong Answer

Solution code:
s = input()
s = [ord(ss) for ss in s]
flag = []
for i in range(ord('a'), ord('z')+1):
  if i in s:
    flag.append(i)
if len(set(flag)) == 28:
  print('None')
else:
  for i in range(ord('a'), ord('z')+1):
    if i not in flag:
      print(chr(i))
      break

Submission status: Wrong Answer

Solution code:
s = input()
s = [ord(ss) for ss in s]
flag = []
for i in range(ord('a'), ord('z')+1):
  if i in s:
    flag.append(i)
if len(set(flag)) == 28:
  print('None')
else:
  for i in range(ord('a'), ord('z')+1):
    if i not in flag:
      print(chr(i))

Submission status: Wrong Answer

Solution code:
s = input()
s = [ord(ss) for ss in s]
flag = []
for i in range(ord('a'), ord('z')+1):
  if i in s:
    flag.append(i)
for i in range(ord('a'), ord('z')+1):
  if i not in flag:
    print(chr(i))
    break

Submission status: Wrong Answer

Solution code:
s = input()
s = [ord(ss) for ss in s]
flag = False
for i in range(ord('a'), ord('z')+1):
  if i in s:
    flag = True
    ans = chr(i)
if flag:
  print(ans)
else:
  print('None')

Submission status: Wrong Answer

Solution code:
s1 = sorted(input())
s2 = "abcdefghijklmnopqrstuvwxyz"

for s in s1:
  if s in s2:
    pass
  else:
    print(s)
    break
else:
  print("None")

Submission status: Wrong Answer

Solution code:
S = list(input())
S.sort()

tmp = S[0]
if tmp != 'a':
    print('a')
    exit()

for i in S:
    if ord(i) == (ord(tmp) + 1) or ord(i) == ord(tmp):
        tmp = i
    else:
        print(chr(ord(i)-1))
        exit()

if tmp == 'z':
    print("None")

Submission status: Wrong Answer

Solution code:
s = list(input())
alphabet = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v' ,'w', 'x', 'y', 'g'}
ans = sorted(list(alphabet - set(s)))
if len(ans) == 0:
    ans = 'None'
else:
    ans = ans[0]
print(ans)

Submission status: Wrong Answer

Solution code:
S = input()
if len(set(S)) == 26:
    print('None')
else:
    ss = sorted(list(set(S)))
    alpah = [i for i in 'abcdefghijklmnopqrstuvwxyz']
    for i in range(len(ss)):
        if alpah[i] != ss[i]:
            print(alpah[i])
            break

Submission status: Wrong Answer

Solution code:
s=input()
s=set(s)
l = list(s)
l.sort()
al=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
for i in range(len(l)):
    if(l[i]!=al[i]):
        print(al[i])
        break
if (l==al):
    print('None')

Submission status: Wrong Answer

Solution code:
s = input().split()
s = list(s[0])
s.sort()
alf = [chr(i) for i in range(97, 97+26)] 
Flag = 0
j = 0
for i in range(len(s)):
    if s[i] == alf[j]:
        continue
    j += 1
    if s[i] == alf[j]:
        continue
    else:
        print(alf[j])
        Flag = 1
        break
if Flag == 0:
    print("None")

Submission status: Wrong Answer

Solution code:
s = input().split()
s = list(s[0])
s.sort()
alf = [chr(i) for i in range(97, 97+26)] 

j = 0
for i in range(len(s)):
    if s[i] == alf[j]:
        continue
    j += 1
    if s[i] == alf[j]:
        continue
    else:
        print(alf[j])
        break

Submission status: Wrong Answer

Solution code:
s=list(input())
a=["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]
d=list(set(s))
d.sort()
ans="None"
for i in range(min(len(a),len(d))):
    if d[i]!=a[i]:
        ans=a[i]
        break
print(ans)

Submission status: Wrong Answer

Solution code:
# coding: utf-8
# Your code here!

def num2alpha(num):
    if num <= 26:
        return chr(64 + num)
    elif num % 26==0:
        return num2alpha(num // 26 - 1)+chr(90)
    else:
        return num2alpha(num // 26) + chr(64 + num % 26)

s = list(input().upper())
for i in range(1, len(s) + 1):
    if num2alpha(i) in s:
        continue
    else:
        print(num2alpha(i).lower())
        break
else:
    print("None")

Submission status: Wrong Answer

Solution code:
s=input()
for i in "abcdefghijklmopqrstuvwxyz":
  if i in s:continue
  print(i)
  break

Submission status: Wrong Answer

Solution code:
s = input()
s_set = list(set(s))    #重複削除

s_set.sort()

chk = list("abcdefghijklmnopqrstuvwxyz")

i = 0

while 1:
    if s_set[i] != chk[i]:
        print(chk[i])
        break
    i += 1
    if i >= 26 or i>=len(s_set):
        print("None")
        break

Submission status: Wrong Answer

Solution code:
import string#WA
s = input().split()
pa = []
for i in s:
    seta = True
 #   for pre in pa:
#        if i == pre:
#            seta = False
#            break
    if seta:
        pa.append(i)
for al in str(string.ascii_lowercase):
    printa = True
    for pre in pa:
        printa = False
    if printa:
        print(al)
        break

Submission status: Wrong Answer

Solution code:
from sys import stdin
S = (stdin.readline().rstrip())
if len(set(list(S))) == 26:
    print("None")
else:
    print(sorted(set(list(S)))[0])

Submission status: Wrong Answer

Solution code:
s = input()
temp = 'abcdefghijklmnopqrstuvwxyz'
for i in range(26):
  if s.find(temp[i])>-1:
    print(temp[i])
    break
print('None')

Submission status: Wrong Answer

Solution code:
s=input()
a='abcdefghijklmnopqrstuvwxyz'
for i in range(26):
  if a[i] not in s:
    print(a[i])
    break

Submission status: Wrong Answer

Solution code:
word = input()
print(word)

Submission status: Wrong Answer

Solution code:
s = input()
S = list(set(s))
list.sort(S)
strings = "abcdefghijklmnopqrstuvwxyz"
switch = 0
for i in S:
    if i != strings[S.index(i)]:
        print(strings[S.index(i)])
        switch = 1
        break
    else:
        continue
if switch == 0:
    print(None)

Submission status: Wrong Answer

Solution code:
S= input()

abs = 'abcdefghijklmnopqrstuvwxyz'

for ab in abs:
  if ab in S:
    print(ab)
    exit()
else: print('None')

Submission status: Wrong Answer

Solution code:
S= input()

abs = 'abcdefghijklmnopqrstuvwxyz'

for ab in abs:
  if ab in S: print(ab)
else: print('None')

Submission status: Wrong Answer

Solution code:
S= input()

abs = 'abcdefghijklmnopqrstuvwxyz'

for ab in abs:
  if ab in S: print(ab)

Submission status: Wrong Answer

Solution code:
import sys

s = list(set(list(input())))
s.sort()
#print(s)
for i in range(len(s)):
    if s[i] != chr(ord("a") + i):
        print(chr(ord("a") + i))
        sys.exit()
print("None")

Submission status: Wrong Answer

Solution code:
import sys

s = list(input())
set_s = set(s)
new_s = list(set_s)
new_s.sort()
for i in range(26):
    if ord(new_s[i]) != 97+i:
        print(chr(97+i))
        sys.exit()
    if len(new_s) == i+1:
        print(chr(98+i))
        sys.exit()
print('None')

Submission status: Wrong Answer

Solution code:
s = sorted(list(set(input())))
t = "abcdefghijklmnopqrstuvwxyz"

ans = "None"
for i in range(len(s)-1):
	if s[i] != t[i]:
		ans = (t[i])
		break
print(ans)

Submission status: Wrong Answer

Solution code:

s = sorted(list(set(input())))
t = "abcdefghijklmnopqrstuvwxyz"

ans = "None"
for i in range(len(s)):
	if s[i] != t[i]:
		ans = (t[i])
		break
print(ans)

Submission status: Wrong Answer

Solution code:

t = list("abcdefghijklmnopqrstuvwxyz")
s = sorted(list(set(input())))

if len(t) == len(s):
	print("None")
else:	
	for i in range(len(s)):
		if s[i] != t[i]:
			print(t[i])
			break

Submission status: Wrong Answer

Solution code:
s = input()
alpha = "abcdefghijklmnopqrstuvwxyz"

for a in alpha :
	if a not in s :
		print(a)
		break

Submission status: Wrong Answer

Solution code:
#alphabet="abcdefghijklmnopqrstuvwxyz"
alphabet = []
S=list(set(input()))
S.sort()
for i in range(26):
    alphabet.append(chr(ord('a')+i))
for i in range(len(S)):
    if alphabet[i]!=S[i]:
        print(alphabet[i])
        exit()
print("None")

Submission status: Wrong Answer

Solution code:
alphabet="abcdefghijklmnopqrstuvwxyz"
S=input()
s=[]
for i in range(len(S)):
    s.append(S[i])
s = list(set(s))
s.sort()
#print(s)
for i in range(len(s)):
    if alphabet[i]!=s[i]:
        print(alphabet[i])
        exit()
print("None")

Submission status: Wrong Answer

Solution code:
S = [ord(c) for c in list(input())]

def main():
    ans = None
    for n in range(ord('a'), ord('z')):
        if S.count(n) == 0:
            ans = chr(n)
            break
    print(ans)

if __name__ == '__main__':
    main()

Submission status: Wrong Answer

Solution code:
s=input()
alp='abcdefghijklmnopqrstuvwxyz'
for i in range(25):
  if alp[i] not in s:
    print(alp[i])
    break
else:
  print('None')

Submission status: Wrong Answer

Solution code:
s=list(input())
s=list(set(s))
s.sort()
key='A'
for i in range(len(s)-1):
    if s[i+1]!=chr(ord(s[i])+1):
        key=chr(ord(s[i])+1)
        break
            
if len(s)==1:
    print(chr(ord(s[0])+1))
elif len(s)==26:
    print('None')
elif key!='A': print(key)
else: print(chr(ord(s[len(s)-1])+1))

Submission status: Wrong Answer

Solution code:
s=list(input())
s=list(set(s))
s.sort()
key='A'
for i in range(len(s)-1):
    if s[i+1]!=chr(ord(s[i])+1):
        key=chr(ord(s[i])+1)
        break
        
if key!='A':
    print(key)
else: 
    print('None')

Submission status: Wrong Answer

Solution code:
import sys
input = sys.stdin.readline

a = set(map(chr, range(ord('a'), ord('z')+1)))
s = set(input())
ans = a-s
print(min(ans)) if ans else 'None'

Submission status: Wrong Answer

Solution code:
S = input()
for c in 'abcdefghijklmnopqrstuvwxyz':
  if S.count(c) == 0:
    print(c)
    exit()

Submission status: Wrong Answer

Solution code:
S = input()
A = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"] 
B = [0]*26
flag = -1

for i in range(len(S)):
  
  for j in range(len(A)):
    if S[i] == A[j]:
      B[j] += 1
      break
  
  if i == len(S):
    break

for k in range(len(B)):
  if B[k] == 0:
    print(A[k])
    flag = 1
    break
    
if flag == -1:
  print("none")

Submission status: Wrong Answer

Solution code:
# 入力
S=input()

# a〜z
l=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']

for x in l:
  if x in S:
    print(x)
    exit()

print('None')

Submission status: Wrong Answer

Solution code:
#https://atcoder.jp/contests/abc071/tasks/abc071_b
import string
S = list(input())
S.sort()
alf = string.ascii_lowercase
for i in range(len(S)):
    if alf[i] != S[i]:
        print(alf[i])
        break
    elif i ==len(S)-1:
        print("None")

Submission status: Wrong Answer

Solution code:
s=set(list(input()))
alpha=list("abcdefghijklmnopqrstuvwxyz")
for a in alpha:
    if a in s:
        alpha.remove(a)
if alpha == []:
    print("None")
else:
    print(alpha[0])

Submission status: Wrong Answer

Solution code:
s=sorted(set(list(input())))[0]
alpha=list("bcdefghijklmnopqrstuvwxyz")
if s == "a":
    print("None")
for i in range(len(alpha)):
    if alpha[i] == s:
        print(alpha[i-1])
        break

Submission status: Wrong Answer

Solution code:
s = input()
binary = {}
alphabet = "abcdefghijklmnopqrstuvwxyz"
flag = False
for i in alphabet:
    binary[i] = 0
for j in s:
    binary[j] = 1
if 0 not in binary:
    flag = True
for k in alphabet:
    if binary[k] == 0:
        print(k)
        break
if flag:
    print("None")

Submission status: Wrong Answer

Solution code:
s = input()
binary = {}
alphabet = "abcdefghijklmnopqrstuvwxyz"

for i in alphabet:
    binary[i] = 0
for j in s:
    binary[j] = 1
for k in alphabet:
    if binary[k] == 0:
        print(k)
        break
    elif 0 in binary:
        print("None")
        break

Submission status: Wrong Answer

Solution code:
"""
文字列lの？個目が文字列Sに含まれたらansの？個目は0，含まれなかったら1
ansの要素を全部足して0だったら文字列Sにはアルファベットが全て含まれる
"""
s=input()
l="abcdefghijklmnopqrstuvwxyz"
ans=[0]*26
for i in range(25):
    if l[i] not in s:
        ans[i]=1
    else:
        ans[i]=0
if sum(ans[x] for x in range(25))>0:
    print(l[ans.index(1)])
else:
    print("None")

Submission status: Wrong Answer

Solution code:
l=list("abcdefghijklmnopqrstuvwxyz")
w=list(input())
for i in l:
  if not(i in w):
    print(i)
    break

Submission status: Wrong Answer

Solution code:
s = input()
for c in "abcdefghijklnmopqrstuvwxy":
    if not c in s:
        print(c)
        exit()
print(None)

Submission status: Wrong Answer

Solution code:
alpha = "abcdefghijklmnopqrstuvwxyz"
S = input()
flag = True
for i in alpha:
  if i in S:
    pass
  else:
    print(i)
    flag = False
    
if flag:
  print("None")

Submission status: Wrong Answer

Solution code:
# encoding:utf-8
import copy
import random
import bisect #bisect_left　これで二部探索の大小検索が行える
import math


S = str(input())

# print(S)
all = list("abcdefghijklmnopqrstu")
all.sort()
for i in range(len(S)):
    if S[i] in all:
        all.remove(S[i])

if len(all) > 0:
    print(all[0])
else:
    print("None")

Submission status: Wrong Answer

Solution code:
# encoding:utf-8
import copy
import random
import bisect #bisect_left　これで二部探索の大小検索が行える
import math


S = str(input())

# print(S)
all = list("abcdefghijklmnopqrstu")
for i in range(len(S)):
    if S[i] in all:
        all.remove(S[i])

if len(all) > 0:
    print(all[0])
else:
    print("None")

Submission status: Wrong Answer

Solution code:
# encoding:utf-8
import copy
import random
import bisect #bisect_left　これで二部探索の大小検索が行える
import math


S = str(input())

print(S)
all = list("abcdefghijklmnopqrstu")
for i in range(len(S)):
    if S[i] in all:
        all.remove(S[i])

if len(all) > 0:
    print(all[0])
else:
    print("None")

Submission status: Wrong Answer

Solution code:
S = input()
import string
alphas = sorted(set(string.ascii_letters.lower()))
for al in alphas:
    if al in S:
        alphas.remove(al)
    else:
        print(al)
        break
if not len(alphas):
    print('None')

Submission status: Wrong Answer

Solution code:
S = input()
import string
alphas = sorted(set(string.ascii_letters.lower()))
for al in alphas:
    if al in S:
        alphas.remove(al)
    else:
        print(al)
        break
else:
    print('None')

Submission status: Wrong Answer

Solution code:
*S, = sorted(set(input()))
for i, s in enumerate(S):
	lowest = ord(s) - 1
	if ord("a") <= lowest and chr(lowest) not in S:
		print(chr(lowest))
		break
else:
	print("None")

Submission status: Wrong Answer

Solution code:
import itertools
from collections import Counter
import bisect

def main():
    s = list(input())
    s = list(set(s))
    s.sort()
    cur = ord('a')
    # print(s)
    for c in s:
        if cur == ord(c):
            cur = cur + 1
        else:
            print(chr(cur))
            exit()
    print('None')


if __name__ == '__main__':
    main()

Submission status: Wrong Answer

Solution code:
import itertools
from collections import Counter
import bisect

def main():
    s = list(input())
    s.sort()
    cur = ord('Z')
    nex = ord('a')
    # print(s)
    for c in s:
        if cur == ord(c):
            continue
        elif nex == ord(c):
            cur = nex
            nex = nex + 1
        else:
            print(chr(nex))
            exit()
    print('None')


if __name__ == '__main__':
    main()

Submission status: Wrong Answer

Solution code:
import itertools
from collections import Counter
import bisect

def main():
    s = list(input())
    s.sort()
    exp = ord('a') - 1
    for c in s:
        if exp == ord(c):
            continue
        elif exp + 1 == ord(c):
            exp += 1
        else:
            print(chr(max(ord('a'), ord(c)-1)))
            exit()
    print('None')


if __name__ == '__main__':
    main()

Submission status: Wrong Answer

Solution code:
import itertools
from collections import Counter
import bisect

def main():
    s = list(input())
    s.sort()
    exp = ord('a') - 1
    for c in s:
        if exp == ord(c):
            continue
        elif exp + 1 == ord(c):
            exp += 1
        else:
            print(chr(ord(c)-1))
            exit()
    print('None')


if __name__ == '__main__':
    main()

Submission status: Wrong Answer

Solution code:
abc=[chr(i) for i in range(97,97+26)]
s=sorted(list(set(input())))
for i in range(len(s)):
    if abc[i]!=s[i]:
        print(abc[i])
        exit()
print('None')

Submission status: Wrong Answer

Solution code:
s=input()
a=sorted(set(s))
E="abcdefghijklmnopqrstuvwxyz"
ans=0
if len(set(a))==26:
  print("None")
else:
  for i in range(len(a)):
    if a[i]!=E[i]:
      print(E[i])
      break
    else:
      ans+=1
  print(E[ans])

Submission status: Wrong Answer

Solution code:
s=input()
a=sorted(set(s))
E="abcdefghijklmnopqrstuvwxyz"
ans=0
if len(set(a))==26:
  print("None")
else:
  for i in range(len(a)):
    if a[i]!=E[i]:
      print(E[i])
      break