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: Accepted

Solution code:
S = input()
mylist=([chr(ord('a') + i) for i in range(26)])
for i in range(26):
    if mylist[0] in S:
        mylist.pop(0)
        pass
    else:
        print(mylist[0])
        break
if mylist==[]:
    print("None")

Submission status: Accepted

Solution code:
# -*- coding: utf-8 -*-

s = input()

lis = set(list(s))

dic = ["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 lis:
    dic.remove(i)

if len(dic) == 0:
    print("None")
else:
    print(dic[0])

Submission status: Accepted

Solution code:
S = input()
origin = set()
for i in range(26):
    origin.add(chr(ord('a') + i))

s = set(S)
li = list(origin - s)
if len(li) == 0:
    print('None')
else:
    print(sorted(li)[0])

Submission status: Accepted

Solution code:
s = input()
alp = [chr(i) for i in range(ord('a'),ord('z')+1)]
ans = []
for i in alp:
    if i not in s:
        ans.append(i)
ans.sort()
if ans:
    print(ans[0])
else:
    print('None')

Submission status: Accepted

Solution code:
S = input().strip()
alph = [chr(i) for i in range(97, 97+26)]
for i in S:
  if i in alph:
    alph.remove(i)
if alph:
  print(alph[0])
else:
  print("None")

Submission status: Accepted

Solution code:
s=list(set(input()))
alph=[chr(i) for i in range(97,97+26)]
for i in s:
    if i in alph:
        alph.remove(i)
if alph:
    print(alph[0])
else:
    print("None")

Submission status: Accepted

Solution code:
s=input()
alph=[chr(i) for i in range(97,97+26)]
for i in s:
    if i in alph:
        alph.remove(i)
if alph:
    print(alph[0])
else:
    print("None")

Submission status: Accepted

Solution code:
s = str(input())
alp = list('abcdefghijklmnopqrstuvwxyz')
lst = []

for i in range(len(s)):
    if s[i] in alp:
        alp.remove(s[i])

if alp==[]:
    print('None')
else:
    alp.sort()
    print(alp[0])

Submission status: Accepted

Solution code:
s=input()
flg=True
for i in range(97,97+26):
  if not chr(i) in s:
    print(chr(i))
    flg=False
    break
if flg:
  print("None")

Submission status: Accepted

Solution code:
s = str(input())
alphabet = list('abcdefghijklmnopqrstuvwxyz')
for i in alphabet:
    if i in s:
        continue
    else:
        print(i)
        exit(0)
print('None')

Submission status: Accepted

Solution code:
l="abcdefghijklmnopqrstuvwxyz"
ans=sorted(set(l)^set(input()))
print("None" if len(ans)==0 else ans[0])

Submission status: Accepted

Solution code:
S=input()
#print(chr(97))

for i in range(26):
    if chr(i+97) not in S:
        ans=chr(i+97)
        break
    else:
        ans="!"
        
if ans=="!":
    print("None")
else:
    print(ans)

Submission status: Accepted

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

l = []

for i in range(26):
    l.append(chr(i+ord("a")))

for i in range(len(S)):
    l.remove(S[i])

if len(l)==0:
    print("None")
else:
    print(l[0])

Submission status: Accepted

Solution code:
s=list(input())
a=[chr(i) for i in range(97,97+26)]
x=0
for i in range(26):
    if s.count(a[i])==0:
        print(a[i])
        x+=1
        break
if x==0:
    print('None')

Submission status: Accepted

Solution code:
s=input()

for i in range(97, 122+1):
    if chr(i) not in s:
        print(chr(i))
        break
    if chr(i) =="z":
        print("None")
        break

Submission status: Accepted

Solution code:
import sys
from collections import defaultdict, deque
import bisect
from heapq import *
from math import factorial
sys.setrecursionlimit(200000)
input = sys.stdin.readline

# X, A, B = map(int, input().split())
# N = int(input())
# L = [int(v) for v in input().split()]
# L = [[int(v) for v in input().split()] for _ in range(N)]
# L = [int(input()) for _ in range(N)]
# L = [list(input().strip())  for _ in range(N)]
S = input().strip()

l = set([v for v in range(97, 123)])
for v in S:
    l = l - {ord(v)}

if len(l) == 0:
    print("None")
    exit()
print(chr(min(l)))

Submission status: Accepted

Solution code:
# -*- coding: utf-8 -*-
 
import math
import itertools
import sys
import copy
 
# 入力
#A, B, C, D = map(int, input().split())
#L = list(map(int, input().split()))
#N = int(input())
S = list(str(input()))
S.sort()
Q = "abcdefghijklmnopqrstuvwxyz"
#print (S)

index = 0
if S[0] == Q[0] :
  index += 1
else :
  print ("a")
  exit()

for i in range(1, len(S)) :
  if index == 26 :
    print ("None")
    exit()
  
  if S[i] == Q[index] :
    index += 1
  else :
    if S[i] == S[i-1] :
      continue
    print (Q[index])
    exit()


if index != 26 :
  print (Q[index])
else :
  print ("None")

Submission status: Accepted

Solution code:
import sys

for i in sys.stdin:
  t = [True for j in range(26)]
  for j in i.strip('\n'):
    t[ord(j) - 97] = False
  for j in range(len(t)):
    if t[j]:
      print(chr(j + 97))
      break
  else:
    print('None')

Submission status: Accepted

Solution code:
import string

s = input()
alp = string.ascii_lowercase

for c in s:
    if c in alp:
        alp = alp.replace(c, '', -1)

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

Submission status: Accepted

Solution code:
import string

S = input()

for s in string.ascii_lowercase:
    if s not in S:
        print(s)
        exit()

print("None")

Submission status: Accepted

Solution code:
k=set("aqwertyuioplkjhgfdsazxcvbnm")
s=set(input())
ks=list(k-s)
if len(ks)==0:
  print("None")
else:
  ks.sort()
  print(ks[0])

Submission status: Accepted

Solution code:
import itertools
s = sorted(set(input()))

ans = "None"
for i, _s in itertools.zip_longest([chr(i) for i in range(97, 97+26)], s):
    if i != _s:
        ans = i
        break

print(ans)

Submission status: Accepted

Solution code:
x=[chr(i) for i in range(97, 97+26)]
y=[0]*26
s=input()
for i in s:
    y[x.index(i)]=1
for i in range(26):
    if y[i]==0:
        print(chr(97+i))
        break
else:
    print("None")

Submission status: Accepted

Solution code:
s = input()

letters = list(map(chr, range(97, 123)))
ans = sorted(set(letters) - set(s))

print(ans[0] if ans else 'None')

Submission status: Accepted

Solution code:
S = str(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 range(len(S)):
  if S[i] in a:
    a.remove(S[i])
print(None if a==[] else a[0])

Submission status: Accepted

Solution code:
S = input()
ABC = ['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(ABC)):
 if ABC[i] not in S:
  print(ABC[i])
  exit()
else:
  print("None")

Submission status: Accepted

Solution code:
S = set(input())
alp = "abcdefghijklmnopqrstuvwxyz"
ans = [i for i in alp if not i in S]
if len(ans) == 0:
    print("None")
else:
    print(ans[0])

Submission status: Accepted

Solution code:
S = input()

a_to_z = "abcdefghijklmnopqrstuvwxyz"
ans = [0 for i in range(26)]
for i in range(26):
    if a_to_z[i] not in S:
        ans[i] = 1
    else:
        ans[i] = 0
        
if sum(ans[x] for x in range(26)) > 0:
    print(a_to_z[ans.index(1)])
else:
    print("None")

Submission status: Accepted

Solution code:
S = list(input())
alpha_list = [chr(i) for i in range(97,97+26)]

S = set(S)
alpha_list = set(alpha_list)
answer = alpha_list - S
if alpha_list == S:
    print('None')
else:
    print(sorted(list(answer))[0])

Submission status: Accepted

Solution code:
alp = {i for i in "abcdefghijkmlnopqrstuvwxyz"}
s = set(input())

l = sorted(list(alp - s))
if l:
    print(l[0])
else:
    print("None")

Submission status: Accepted

Solution code:
import sys
from string import ascii_lowercase

s = sys.stdin.readline().rstrip()

def main():
    res = sorted(set(ascii_lowercase) - set(s))
    return res[0] if res else None

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

Submission status: Accepted

Solution code:
S = input()

words = set(list(S))

alphabets = set(list("abcdefghijklmnopqrstuvwxyz"))


or_set = sorted(alphabets - words)
if or_set:
    print(or_set[0])
else:
    print("None")

Submission status: Accepted

Solution code:
S = input()

bucket = [0] * 26


def c_to_num(c):
    return ord(c) - 97


def num_to_c(num):
    return chr(num+97)


for c in S:
    bucket[c_to_num(c)] += 1

ret = 'None'
for i, n in enumerate(bucket):
    if not n:
        ret = num_to_c(i)
        break

print(ret)

Submission status: Accepted

Solution code:
s = set(input())
l = set(chr(i) for i in range(ord("a"), ord("z") + 1))

for i in sorted(l):
    if not i in s:
        print(i)
        break
    if i == "z":
        print("None")

Submission status: Accepted

Solution code:
s = input()
alpha = [chr(ord('a') + i) for i in range(26)]
for letter in s:
    if(alpha.count(letter)): alpha.remove(letter)
print(alpha[0]) if alpha else print('None')

Submission status: Accepted

Solution code:
li = list("abcdefghijklmnopqrstuvwxyz")
s = list(input())
cnt = [0 for i in range(26)]


for i in range(len(s)):
    for j in range(26):
        if li[j]==s[i]:
            cnt[j]+=1

for i in range(26):
    if cnt[i]==0:
        print(li[i])
        break
    elif i ==25:
        print("None")

Submission status: Accepted

Solution code:
s = input()

al = [chr(ord('a') + i) for i in range(26)]
al.sort()
s = set(s)
ans = 'None'
for a in al:
    if a not in s:
        ans = a
        break
print(ans)

Submission status: Accepted

Solution code:
#coding:utf-8
s = input()
letter  = 'abcdefghijklmnopqrstuvwxyz'
s_sort = sorted(s)


for l in letter:
    if l not in s_sort:
        print(l)
        exit()

print("None")

Submission status: Accepted

Solution code:
s = list(input())
alp = list("abcdefghijklmnopqrstuvwsyz")
for i in alp:
    if i not in s:
        print(i)
        exit()
print('None')

Submission status: Accepted

Solution code:
s=list(input())
dic=[]
for i in range(26):
    dic.append([chr(i+97),0])
#print(dic)
num=lambda x:ord(x)-ord("a")
for i in range(len(s)):
    if dic[num(s[i])][1]==0:
        dic[num(s[i])][1]=1
exit=0
ans=0
for i in range(26):
    if dic[i][1]==0:
        exit=1
        ans=i
        break
print(dic[i][0] if exit==1 else "None")

Submission status: Accepted

Solution code:
s = input()
for i in range(26):
    a = chr(ord("a") + i) #文字コードをaから数えて26個分
    if a not in s:
        print(a)
        break
else: # for文にもelseを付けられる.
    print("None")

Submission status: Accepted

Solution code:
s=input()
alp="abcdefghijeklmnopqrstuvwxyz"
for i in alp:
    if i not in s:
        print(i)
        exit()
print("None")

Submission status: Accepted

Solution code:
import collections
dd = collections.defaultdict(bool)
s = input()
for i in s:
    dd[i] = True
for i in range(ord('a'), ord('z') + 1):
    if not dd[chr(i)]:
        print(chr(i))
        exit()
print('None')

Submission status: Accepted

Solution code:
alpha = {i.lower() for i in 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'}
s = set(input())

l = sorted(list(alpha - s))

print(l[0] if l else 'None')

Submission status: Accepted

Solution code:
import string

s = str(input())

s_set = set(s)
alpha_set = set(string.ascii_lowercase)

res = list(alpha_set - s_set)

if len(res) == 0:
    ans = 'None'
else:
    ans = sorted(res)[0]

print(ans)

Submission status: Accepted

Solution code:
s=input()
ls=list("abcdefghijklmnopqrstuvwxyz")
ans = "None"
for i in ls:
  if i not in s:
    ans = i
    break
print(ans)

Submission status: Accepted

Solution code:
import string
s=input()
for alpha in string.ascii_lowercase:
    if(alpha not in s):
        print(alpha)
        exit()
print('None')

Submission status: Accepted

Solution code:
s=set(input())
al=set([chr(ord('a') + i) for i in range(26)])
ans=list(al-s)
if ans!=[]:
	ans.sort()
	print(ans[0])
else:print('None')

Submission status: Accepted

Solution code:
s = input()
ch = [chr(i) for i in range(97, 97+26)]

for c in ch:
    if  c not in s:
        print(c)
        import sys
        sys.exit()
print("None")

Submission status: Accepted

Solution code:
x=[chr(i) for i in range(97, 97+26)]
s=input()
for i in x:
    if i not in s:
        print(i)
        break
else:
    print("None")

Submission status: Accepted

Solution code:
line = input()
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"]
letters = []
for i in range(len(line)):
  letters.append(line[i])
setted = sorted(set(letters))
for j in alpha[:]:
  for k in setted:
    if j == k:
      alpha.remove(j)
if len(alpha) == 0:
  print("None")
else:
  answer = alpha[0]
  print(answer)

Submission status: Accepted

Solution code:
Alph = "abcdefghijklmnopqrstuvwxyz"
S = list(input())
S.sort()
ans = "None"
for i in Alph:
        if i not in S:
                ans = i 
                break
print(ans)

Submission status: Accepted

Solution code:
print((sorted(list({chr(i) for i in range(ord('a'),ord('z')+1)}-set(input())))+[None])[0])

Submission status: Accepted

Solution code:
S = input()

hoge = ['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']

hoge2 = list(S)

differlen = len((set(hoge) ^ set(hoge2)))

differ2 = set(hoge) ^ set(hoge2)
differ3 = sorted(differ2)




if differlen == 0:
    print("None")
else:
    print(differ3[0])

Submission status: Accepted

Solution code:
S = sorted(list(input()))
S = list(map(lambda x: ord(x) - ord('a'), S))
S = list(set(S))

for i in range(26):
    if i not in S:
        print(chr(i + ord('a')))
        break
else:
    print('None')

Submission status: Accepted

Solution code:

def main()->None:
    alphabet = "abcdefghijklmnopqrstuvwxyz"
    S = input()
    sorted_s = sorted(S)
    flag = False
    for i in alphabet:
        if i not in sorted_s:
            flag = True
            break
    if flag:print(i)
    else:print("None")



if __name__ == "__main__":
    main()

Submission status: Accepted

Solution code:
s = sorted(set(input()))
t = "abcdefghijklmnopqrstuvwxyz"
ans = "None"
for tt in t:
  if not tt in s:
    ans = tt
    break
print(ans)

Submission status: Accepted

Solution code:
s = 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", "z", ]

for i in alphabet:
    if i not in s:
        print(i)
        break
else:
    print("None")

Submission status: Accepted

Solution code:
s = sorted(input())
characters = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','t','u','v','w','x','y','z']
ans = "None"
for i in characters:
      if i not in s:
        ans = i
        break
print(ans)

Submission status: Accepted

Solution code:
s=input()
l=[]
alf=["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 alf:
    if str(x) in s:
        pass
    else:
        l.append(x)
if l==[]:
    print("None")
else:
    print(min(l))

Submission status: Accepted

Solution code:
print((list(sorted(set(chr(ord("a") + i) for i in range(26)) - set(input()))) + ["None"])[0])

Submission status: Accepted

Solution code:
[print(un_appearence[0] if un_appearence else "None") for un_appearence in [[chr(i) for i in range(ord('a'), ord('z') + 1) if chr(i) not in string] for string in [input()]]]

Submission status: Accepted

Solution code:
from collections import Counter
S = list(input())
S = Counter(S)
S = list(S.keys())
S.sort()
for i in range(26):
    alph = chr(ord("a") + i)
    #print(alph)
    if i == len(S):
        print(chr(ord("a") + i))
        exit()
    elif S[i] != chr(ord("a") + i):
        print(alph)
        exit()

print("None")

Submission status: Accepted

Solution code:
s = input()

ls_small = [chr(_) for _ in range(97, 97+26)]

for i in range(len(ls_small)):
    if ls_small[i] not in s:
        print(ls_small[i])
        break
    elif i == len(ls_small) - 1:
        print("None")

Submission status: Accepted

Solution code:
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():
    find=[False]*26
    orda=ord("a")
    for c in input():
        find[ord(c)-orda]=True
    for i in range(26):
        if not find[i]:
            print(chr(i+97))
            break
    else:
        print("None")
main()

Submission status: Accepted

Solution code:
s = input()

for i in range(ord("a"),ord("z")+1):
    if chr(i) not in s:
        print(chr(i))
        quit()
print('None')

Submission status: Accepted

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"]
ls2=["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(S)):
  for j in range(len(ls)):
    if S[i] == ls[j]:
      if ls[j] in ls2:
        ls2.remove(ls[j])
      break
if len(ls2) == 0:
  print("None")
else:
  print(ls2[0])

Submission status: Accepted

Solution code:
S=input()

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

try:
    print(sorted(list(set(atoz)-set(S)))[0])
except:
    print(None)

Submission status: Accepted

Solution code:
a = set(input())
b = set([chr((ord("a") + i)) for i in range(26)])
print(sorted(list(b-a))[0] if b-a else "None" )

Submission status: Accepted

Solution code:
word = input()
al = [chr(ord("a") + i) for i in range(26)]
d = "None"
for i in al:
    if not i in word:
        d = i
        break
print(d)

Submission status: Accepted

Solution code:
word = input()
al = "qwertyuiopasdfghjklzxcvbnm"
d = []
for i in range(len(al)):
    if not al[i] in word:
        d.append(al[i])
if d == []:
    print("None")
else:
    print(sorted(d)[0])

Submission status: Accepted

Solution code:

S = input()

ans = "None"

a = [chr(ord("a") + i) for i in range(26)]

for i in a:
    if i not in S:
        ans = i
        break

print(ans)

Submission status: Accepted

Solution code:
s = input()
alfa = [chr(i) for i in range(97, 97+26)]
for i in range(len(alfa)):
    for j in range(len(s)):
        if alfa[i] == s[j]:
            alfa[i] = "-"
for i in range(len(alfa)):
    if alfa[i] != "-":
        ans = alfa[i]
        break
    else:
        ans = "None"
print(ans)

Submission status: Accepted

Solution code:
#Not Found
S = input()
ab = [chr(ord('a') + i) for i in range(26)]
c = ""

for a in ab:
    if a in S:
        pass
    else:
        c = a
        break

if c == "":
    c = "None"

print(c)

Submission status: Accepted

Solution code:
s = input()
s = sorted(list(s))
alphabets = set(list('abcdefghijklmopqrstuvwxyz'))
Answer = alphabets - set(s)
Answer = sorted(Answer)
if len(Answer) ==0:
  print('None')
else:
  print(Answer[0])

Submission status: Accepted

Solution code:
al = 'abcdefghijklmnopqrstuvwxyz'
s = input()

s_set = set(list(s))
s_list = list(s_set)
if len(al) == len(s_list):
  print('None')

for a in al:
  if a not in s_list:
    print(a)
    exit(0)

Submission status: Accepted

Solution code:
S = input()
ans = "None"
alphabet = [chr(ord("a") + i) for i in range(26)]

for s in alphabet:
    if s not in S:
        ans = s
        break

print(ans)

Submission status: Accepted

Solution code:
import string

S = str(input())
ans = "None"

for s in string.ascii_lowercase:
    if s not in S:
        ans = s
        break

print(ans)

Submission status: Accepted

Solution code:
import string

S = input()
ans = "None"

for s in string.ascii_lowercase:
    if s not in S:
        ans = s
        break

print(ans)

Submission status: Accepted

Solution code:
s = input()
word = ['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 = sorted(s)
if len(set(s)) == len(word):
  print('None')
  exit()
ans = [i for i in word if i not in s]
print(ans[0])

Submission status: Accepted

Solution code:
S = input()
alpha = [chr(i) for i in range(97,123)]

for s in S:
    if s not in alpha:continue
    alpha.remove(s)
print(alpha[0]) if alpha else print("None")

Submission status: Accepted

Solution code:
alfa = [chr(i) for i in range(97, 97+26)]
S = str(input())
check = 0
for i in alfa:
    if i not in S:
        check = 1
        print(i)
        break

if check == 0:
    print('None')

Submission status: Accepted

Solution code:
def main():
    s = str(input())

    if not (1 <= len(s) and len(s) <= 10**5):
        return
    if s.islower() == False:
        return
        
    alph = 'abcdefghijklmnopqrstuvwxyz'

    for i in alph:
        if i not in s:
            print(i)
            return
    
    print('None')

if __name__ == "__main__":
    main()

Submission status: Accepted

Solution code:
import sys

S = input()
alphabet_code = list(range(26))

i = 0
j = 0
while i < len(S):
    while j < 26:
        if ord(S[i]) == alphabet_code[j] + 97:
            alphabet_code[j] = -1
        j += 1
    j = 0
    i += 1

while j < 26:
    if alphabet_code[j] != -1:
        print(chr(alphabet_code[j] + 97))
        sys.exit(0)
    j += 1
print("None")

Submission status: Accepted

Solution code:
##### 解けた #####

import string
import numpy as np

a=set(list(string.ascii_lowercase)) # aの集合
S=set(list(input())) # Sの集合
ans=sorted(list(a-S)) # aには含まれるが、Sには含まれないアルファベットのリスト、アルファベット順

if len(ans)>0: # 含まれないものがある場合
    print(ans[0])
else: # 全て含まれる場合
    print("None")

Submission status: Accepted

Solution code:
S = [j for j in input()]
x = [chr(i) for i in range(97,97+26)]
x.append("None")
S.sort()

for p in x:
  if p not in S:break

print(p)

Submission status: Accepted

Solution code:
S=input()
moji=sorted(list(S))
flg=True
for i in range(97,123):
    if chr(i) not in moji:
        print(chr(i))
        flg=False
        break
if flg: print("None")

Submission status: Accepted

Solution code:
from sys import stdin
import bisect

s = stdin.readline().rstrip()

li = "abcdefghijklmnopqrstuvwxyz"

for i in li:
    if i not in s:
        print(i)
        exit()

print("None")

Submission status: Accepted

Solution code:
s = input()

#文字列をリスト化
s = list(s)
s = set(s)
s = sorted(s)

#print(s)

t = 'abcdefghijklmnopqrstuvwxyz'
t = list(t)
#print(t)

if s == t:
	print('None')
else:
	for i in range(len(t)):
		#print(i)
		if i == 25:
			print(t[i])
			break
		elif s[i]!=t[i]:
			print(t[i])
			break

Submission status: Accepted

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

Z=list('abcdefghijklmnopqrstuvwxyz')
for i in Z:
    if i in S:
        continue
    else:
        print(i)
        break
else:
    print('None')

Submission status: Accepted

Solution code:
S = input()
string = [chr(i) for i in range(97, 97+26)]
ans = True
for i in string:
    if((i in S) == False):
        print(i)
        ans = False
        break
if(ans):
    print("None")

Submission status: Accepted

Solution code:
s = input()
LetterInS = set(s)
import string
LetterInAlphabets = set(string.ascii_lowercase)
if LetterInAlphabets - LetterInS == set() :
    print("None")
else :
    LetterSurplus = LetterInAlphabets - LetterInS
    ListSurplus = sorted(list(LetterSurplus))
    print(ListSurplus[0])

Submission status: Accepted

Solution code:
x=input()
s=["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 s:
  if x.count(i)==0:
    print(i)
    exit()
print("None")

Submission status: Accepted

Solution code:
s=input()
a="abcdefghijklmnopqrstuvwxyz"
for i in a:
    if not i in s:
        print(i)
        exit()
print('None')

Submission status: Accepted

Solution code:
import sys
import math

def main():
  S = list(input())
  alphabets = set(list('abcdefghijklmnopqrstuvwxyz'))
  for s in S:
    alphabets.discard(s)
  if len(alphabets) == 0:
    print('None')
  else:
    left = list(alphabets)
    left.sort()
    print(left[0])

main()

Submission status: Accepted

Solution code:
s = input()
abc = 'abcdefghijklmnopqrstuvwxyz'
for i in abc:
    if i not in s:
        print(i)
        exit()
print('None')

Submission status: Accepted

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

Submission status: Accepted

Solution code:
s=input()
l=[chr(i) for i in range(ord('a'),ord('z')+1)]#アルファベットのリストを生成
s=set(s)
ans=''
for i in l:
    if i not in s:
        ans=i
        break
    if len(s)==26:
        ans='None'
print(ans)

Submission status: Accepted

Solution code:
letter="abcdefghijklmnopqrstuvwxyz"
ans=sorted(set(letter)^set(input()))
print("None" if len(ans)==0 else ans[0])

Submission status: Accepted

Solution code:
string = input()
count_array = [0]*26
alphabets = "abcdefghijklmnopqrstuvwxyz"
cha_to_idx = {cha: i for i, cha in enumerate(alphabets)}
for cha in string:
    count_array[cha_to_idx[cha]] = 1

for i, count in enumerate(count_array):
    if count == 0:
        print(alphabets[i])
        break
    elif (count>=1) & (i == 25):
        print("None")

Submission status: Accepted

Solution code:
s = input()
l = [a for a in "abcdefghijklmnopqrstuvwxyz" if a not in s]
print(l[0] if l else "None")

Submission status: Accepted

Solution code:
S = input()
alphabet = 'abcdefghijklmnopqrstuvwxyz';
ans = list(set(alphabet) - set(S))
ans.sort()
if not ans:
   print('None');
else:
    print(ans[0])

Submission status: Accepted

Solution code:
s = sorted(set(input()))
alp = 'abcdefghijklmnopqrstuvwxyz'

ans = 'None'
for i in alp:
    if i in s:
        pass
    else:
        ans = i
        break

print(ans)

Submission status: Accepted

Solution code:
s = input()
abc = "abcdefghijklmgopqrstuvwxyz"
for i in abc:
    if not s.count(i):
        print(i)
        break
else:
    print("None")

Submission status: Accepted

Solution code:
S = str(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 range(len(S)):
  if S[i] in a:
    a.remove(S[i])
print(None if a==[] else a[0])

Submission status: Accepted

Solution code:
def examB():
    St = S()
    AZ = [chr(i) for i in range(97, 97 + 26)]
    ans = "None"
    for s in AZ:
        if s not in St:
            ans = s
            break
    print(ans)

import sys
import copy
import bisect
import heapq
from collections import Counter,defaultdict,deque
def I(): return int(sys.stdin.readline())
def LI(): return list(map(int,sys.stdin.readline().split()))
def LS(): return sys.stdin.readline().split()
def S(): return sys.stdin.readline().strip()
mod = 10**9 + 7
inf = float('inf')

examB()

Submission status: Accepted

Solution code:
# ABC 071: B – Not Found
s = input()
alphabets = 'abcdefghijklmnopqrstuvwxyz'

for c in alphabets:
    if c not in s:
        print(c)
        break
else:
    print('None')

Submission status: Accepted

Solution code:
S = sorted(list(str(input())))
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 i in range(len(l)):
  if not l[i] in S:
    print(l[i])
    break
  if i == len(l) - 1:
    print('None')

Submission status: Accepted

Solution code:
S = input()
abc = "abcdefghijklmnopqrstuvwxyz"
for a in abc:
    if not S.count(a):
        print(a)
        break
else:
    print("None")

Submission status: Accepted

Solution code:
s=list(input())
s=set(s)
al=[chr(i) for i in range(97, 97+26)]
for i in range(len(al)):
    if al[i] not in s:
        print(al[i])
        break
    if i==len(al)-1:
        print('None')

Submission status: Accepted

Solution code:
s=sorted(set(input()))
l=list(range(ord("a"),ord("z")+1))
if len(s) == len(l):
    print("None")
else:
    for i in range(len(s)):
        if ord(s[i]) == l[i]:
            pass
        else:
            print(chr(l[i]))
            exit()
    print(chr(ord(s[-1]) + 1))

Submission status: Accepted

Solution code:
A = input()
alpha = set('abcdefghijklmnopqrstuvwsyz')
a = set(A)
a = alpha.difference(a)
if len(a) == 0:
  print('None')
else:
  a = sorted(list(a))
  print(a[0])

Submission status: Accepted

Solution code:
s=list(input())
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 i in l:
    if i not in s:
        print(i)
        exit()
print("None")

Submission status: Accepted

Solution code:
S = input()
for ch in 'abcdefghijklmnopqrstuvwxyz':
  if ch not in S:
    print(ch)
    exit()
print('None')

Submission status: Accepted

Solution code:
s = list(input())
alp = list("abcdefghijklmnopqrstuvwxyz")
for i in s:
    for j in range(len(alp)):
        if i == alp[j]:
            alp.pop(j)
            break
if len(alp) != 0: print(alp[0])
else: print("None")

Submission status: Accepted

Solution code:
inputStr = input()
inputNum = len(inputStr)
string = "abcdefghijklmnopqrstuvwxyz"
count1, count2 = 0, 0
for i in string:
  count2 = 0
  for j in inputStr:
    if i == j:
      break
    else:
      count2 += 1
  if count2 == inputNum:
    break
  count1 += 1
if count1 == 26:
  print("None")
else:
  print(i)

Submission status: Accepted

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

Submission status: Accepted

Solution code:
S=list(input())
A=list(set(S))
A.sort()
alphabet=list("abcdefghijklmnopqrstuvwxyz")
k='None'
for i in alphabet:
    if not i in A:
        k=i
        break
print(k)

Submission status: Accepted

Solution code:
import string

se = set(list(input()))
alphabet = [s for s in string.ascii_lowercase]

for al in alphabet:
    if al not in se:
        print(al)
        exit()

print('None')

Submission status: Accepted

Solution code:
s=list(input())
a='abcdefghijklmnopqrstuvwxyz'
a_li=list(a)

s_set=set(s)
a_set=set(a_li)

if s_set==a_set:
    print('None')
else:
    result=list(a_set-s_set)
    result.sort()
    print(result[0])

Submission status: Accepted

Solution code:
S = list(set(input()))
for i in range(26):
    if chr(97+i) not in S:
        print(chr(97+i))
        break
else:
    print("None")

Submission status: Accepted

Solution code:
S = list(input())
alpha = [chr(ord('a') + i) for i in range(26)]
for char in alpha:
    if char not in S:
        print(char)
        break
else:
    print(None)

Submission status: Accepted

Solution code:
s = list(input())

alphabet = 'abcdefghijklmnopqrstuvwxyz'
alphabet = list(alphabet)

for i in alphabet:
    if i in s:
        continue
    else:
        print(i)
        exit()

print('None')

Submission status: Accepted

Solution code:
S = set(input())
Alp = list("abcdefghijklmnopqrstuvwxyz")
LL = [i for i in Alp if i not in S]
if LL  == []:
    print("None")
else:
    print(min(LL))