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 = set(input())
Alp = list("abcdefghijklmnopqrstuvwxyz")
MM = []
for i in Alp:
    if i not in S:
        MM.append(i)
if MM == []:
    print("None")
else:
    print(min(MM))

Submission status: Accepted

Solution code:
from collections import Counter,defaultdict,deque
from heapq import heappop,heappush,heapify
import sys,bisect,math,itertools
sys.setrecursionlimit(10**8)
mod = 10**9+7
def inp(): return int(sys.stdin.readline())
def inpl(): return list(map(int, sys.stdin.readline().split()))
def inpln(n): return list(int(sys.stdin.readline()) for i in range(n))

s = input()
t = 'abcdefghijklmnopqrstuvwxyz'
for i in t:
    if not i in s:
        print(i)
        break
else:
    print('None')

Submission status: Accepted

Solution code:
list=["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()
ans=0
for i in list:
	if i not in s:
		print(i)
		ans=i
		break
if ans==0:
	print("None")

Submission status: Accepted

Solution code:
#71b
S = list(input())

setS = set(S)
all_alphabet = set([chr(i) for i in range(97, 97+26)])

not_include_alphabet = list(all_alphabet - setS)
not_include_alphabet.sort(reverse=False)

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

Submission status: Accepted

Solution code:
S = input()
alphabet = "abcdefghijklmnopqrstuvwxyz"
flag = False

for char in alphabet:
    if char not in sorted(set(S)):
        print(char)
        flag = True
        break

if not flag:
    print("None")

Submission status: Accepted

Solution code:
s = input()
ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
for c in s:
    ascii_lowercase = ascii_lowercase.replace(c, "")
if(len(ascii_lowercase) == 0):
    print('None')
else:
    print(ascii_lowercase[0])

Submission status: Accepted

Solution code:
from sys import stdin
from string import ascii_lowercase
s = stdin.readline().rstrip()
not_used = sorted(set(ascii_lowercase) - (set(s) & set(ascii_lowercase)))
print(not_used[0] if not_used else 'None')

Submission status: Accepted

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

Submission status: Accepted

Solution code:
s = set(input())
for i in range(ord('a'),ord("z")+1):
  if not chr(i) in s:
    print(chr(i))
    exit()
print('None')

Submission status: Accepted

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

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

jug = True

for i in range(26):
    if b[i] == 0:
        print(a[i])
        jug = False
        break

if jug == True:
    print("None")

Submission status: Accepted

Solution code:
S=list(input())
S.sort()
c=[]
m=["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(m)):
  if S.count(m[i])==0:
    print(m[i])
    break
  else:
    c.append(m[i])
if c==m:
  print("None")

Submission status: Accepted

Solution code:
S = input()
tmp = list("abcdefghijklmnopqrstuvwxyz")
ans = []
for i in range(len(tmp)):
    if tmp[i] not in S:
        ans.append(tmp[i])
if len(ans) == 0:
    print("None")
else:
    print(ans[0])

Submission status: Accepted

Solution code:
a = input()
abc = [chr(ord('a') + i) for i in range(26)]

for i in abc:
    if i not in a:
        print(i)
        break
    
    if i == 'z':
        print("None")

Submission status: Accepted

Solution code:
alphabet="abcdefghijklmnopqrstuvwxyz"
import collections
table=collections.defaultdict(int)
for x in input():
  table[x]+=1
for x in alphabet:
  if x in table:
    continue
  else:
    print(x)
    exit(0)
print("None")

Submission status: Accepted

Solution code:
import string
alp=string.ascii_lowercase

s=input()
for i in range(26):
  temp=alp[i]
  if temp not in s:
    print(temp)
    exit()
print("None")

Submission status: Accepted

Solution code:
import sys
from functools import reduce
import copy
import math
from pprint import pprint
import collections
import bisect


sys.setrecursionlimit(4100000)


def inputs(num_of_input):
    ins = [input() for i in range(num_of_input)]
    return ins


def int_inputs(num_of_input):
    ins = [int(input()) for i in range(num_of_input)]
    return ins


def solve(inputs):
    s = inputs[0]
    c_set = set()

    for c in s:
        c_set.add(c)

    for c in 'abcdefghijklmnopqrstuvwxyz':
        if c not in c_set:
            return c
    return 'None'


def string_to_int(string):
    return list(map(int, string.split()))


if __name__ == "__main__":
    ret = solve(inputs(1))
    print(ret)

Submission status: Accepted

Solution code:
s = input()

s_s = set(s)
s_a = set(map(chr, range(ord('a'), ord('z') + 1)))
r = ''.join(s_a - s_s) # set to string

if not r:
    print('None')
else:
    print(sorted(r)[0])

Submission status: Accepted

Solution code:
Labc=[chr(i) for i in range(97,97+26)]
Sabc=set(Labc)

S=input()

SS=set()
for c in S:
    SS.add(c)

L=sorted(list(Sabc-SS))
print(L[0] if len(L)>0 else 'None')

Submission status: Accepted

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

alphabet = [chr(ord("a") + i) for i in range(26)]
ans = "None"
for actual, expected in zip(s, alphabet):
    if actual != expected:
        ans = expected
        break

if ans == "None" and s[len(s)-1] != "z":
    ans = alphabet[len(s)]
print(ans)

Submission status: Accepted

Solution code:
S = set(input())
A = set(map(chr, range(ord('a'), ord('z')+1)))

R = A - S

if not R:
  print("None")
else:
  print(sorted(R)[0])

Submission status: Accepted

Solution code:
d='abcdefghijklmnopqrstuvwxyz'
s=input()
for i in d:
  if i not in s:
    print(i)
    break
else:
  print('None')

Submission status: Accepted

Solution code:
n = sorted(list(map(str, input())))
alpha = [chr(ord('a') + i) for i in range(26)]
ans = 'None'

for i in range(26):
  if alpha[i] not in n:
    ans = alpha[i]
    break
print(ans)

Submission status: Accepted

Solution code:
S=set(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']

if len(S)==26:
    print('None')
else:
    for i in range(26):
        if l[i] not in S:
            print(l[i])
            break

Submission status: Accepted

Solution code:
print(min(set(map(chr,range(ord("a"),ord("z")+1)))-set(input())or["None"]))

Submission status: Accepted

Solution code:
s = input()

s_set = set(s)
s_list = list(s_set)
s_list.sort()

afb = "abcdefghijklmnopqrstuvwxyz"

flag = True
for i in afb:
    if i not in s_list:
        flag = False
        print(i)
        break
if flag:
    print("None")

Submission status: Accepted

Solution code:
s = input()
ans = None
for i in range(ord("a"),ord("z")+1):
    if chr(i) not in s:
        ans = chr(i)
        break
print(ans)

Submission status: Accepted

Solution code:
s=input()
tmp='a'
ans=''
while True:
    if s.count(tmp)==0:
        ans=tmp
        break
    if tmp=='z':
        ans=None
        break
    tmp=chr(ord(tmp)+1)
print(ans)

Submission status: Accepted

Solution code:
#2019/10/22
#S = open(0).read()
S = input()
# print(S)
set_S=set(S)
# print(set_S)
alpha = "abcdefghijklmnopqrstuvwxyz"
# print(alpha)
productSet = sorted(set_S^set(alpha))
#print(productSet)
print("None" if len(productSet)==0 else productSet[0])

Submission status: Accepted

Solution code:
s = input()
alphabet = list("abcdefghijklmnopqrstuvwxyz")
for char in alphabet:
  if char not in s:
    print(char)
    exit()
else:
  print("None")

Submission status: Accepted

Solution code:
import string

S = list(input())
T = list(string.ascii_lowercase)
found = 0
for i in range(0, 26):
  for j in range(0, len(S)):
    if T[i] == S[j]:
      break
    if j == len(S)-1:
      print(T[i])
      found = 1
  if found == 1:
    break
  if i == 25:
    print('None')

Submission status: Accepted

Solution code:
S = list(input())
alphabets = [chr(i) for i in range(97, 97 + 26)]
finds = []
for a in alphabets:
    if a not in S and a not in finds:
        finds.append(a)
if len(finds) == 0:
    print('None')
else:
    print(finds[0])

Submission status: Accepted

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

s = input()

flag = True

for c in arr:
    if c not in s:
        print(c)
        flag = False
        break
        
if flag:
    print("None")

Submission status: Accepted

Solution code:
s = input()
a = ord('a')
ans = 'None'
for c in range(a,a+26):
    x = chr(c)
    if not x in s:
        ans = x
        break
print(ans)

Submission status: Accepted

Solution code:
s = sorted(set(input()))
r = "abcdefghijklmnopqrstuvwxyz"
if len(r)-len(s)!=0:
  s +=[""]*(len(r)-len(s))
for i, j in zip(s, r):
  if i != j:
    print(j)
    quit()
print("None")

Submission status: Accepted

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

Submission status: Accepted

Solution code:
s=input()
b=len(s)
a="abcdefghijklmnopqrstuvwxyz"
i=0
while i<b and a!=[]:
  a=a.replace(s[i],"")
  i=i+1
if len(a)!=0:
  print(a[0])
else:
  print("None")

Submission status: Accepted

Solution code:
s=list(set((str(input()))))
s.sort()
s="".join(map(str,s))
t='abcdefghijklmnopqrstuvwxyz'
if s=='abcdefghijklmnopqrstuvwxy':
    print('z')
else:
    for i in range(len(s)):
        if s[i]!=t[i]:
            print(t[i])
            break
    else:
        print(None)

Submission status: Accepted

Solution code:
import sys
S = input()
cnt = [False] * 26
for i in S:
    if i in "abcdefghijklmnopqrstuvwxyz":
        cnt[ord(i) - ord('a')] = True
 
for i in range(len(cnt)):
    if not cnt[i]:
        print(chr(ord('a')+i))
        sys.exit()
print("None")

Submission status: Accepted

Solution code:
import sys
S = input()
alphabet = "abcdefghijklmnopqrstuvwxyz"

for s in alphabet:
    if s not in S:
        print(s)
        sys.exit()

print("None")

Submission status: Accepted

Solution code:
S = input()

alphabet = 'abcdefghijklmnopqrstuvwxyz'

for a in alphabet:
    if a not in S:
        print(a)
        break
else:
    print('None')

Submission status: Accepted

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

Submission status: Accepted

Solution code:
s = [c  for c in input()]
for i in 'abcdefghijklmnopqrstuvwxyz':
  if s.count(i)==0:
    print(i)
    exit()
print('None')

Submission status: Accepted

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

Submission status: Accepted

Solution code:
S = sorted(set(list(input())))
if len(S)==26:
    print("None")
else:
    for i in range(97,123):
        if chr(i) not in S:
            print(chr(i))
            break

Submission status: Accepted

Solution code:
import string
s = input()
flag = 0
for i in range(97,97+26):
  if chr(i) not in s:
    flag = 1
    break
if flag == 0:
  print("None")
else:
   print(chr(i))

Submission status: Accepted

Solution code:
S=set(input())
Al="qwertyuiopasdfghjklzxcvbnm"
AL=list(Al)
l=[]
for i in range(len(Al)):
  if not AL[i] in S:
    l.append(AL[i])
if l!=[]:
  print(sorted(l)[0])
else:
  print("None")

Submission status: Accepted

Solution code:
S = set(input())
A = set("abcdefghijklmnopqrstuvwxyz")
B = sorted(A - S)

if not B:
    print("None")
else:
    print(B[0])

Submission status: Accepted

Solution code:
# ABC071 B - Not Found
S = input()

ABC = 'abcdefghijklmnopqrstuvwxyz'

for s in S:
    if s in ABC:
        ABC = ABC.replace(s,'')

if len(ABC) == 0:
    ans = 'None'
else:
    ans = ABC[0:1]

print(ans)

Submission status: Accepted

Solution code:
D="abcdefghijklmnopqrstuvwxyz"
S=D.strip(input())
if S:print(S[0])
else:print("None")

Submission status: Accepted

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','z','None']

S.sort()

for s in alphabet:
  if s in S:
    pass
  else:
    print(s)
    break

Submission status: Accepted

Solution code:
S = list(input())

for i in range(26):
  if chr(i+97) not in S:
    print(chr(97+i))
    break
    
else:
  print('None')

Submission status: Accepted

Solution code:
s = input()

alpha = 'abcdefghijklmnopqlstuvwxyz'

flag = True
for _ in alpha:
    if _ not in s:
        flag = False
        print(_)
        break

if flag:
    print('None')

Submission status: Accepted

Solution code:
s = set(input())
target = set(list("abcdefghijklmnopqrstuvwxyz"))  
non = list(target-s)
non.sort()
print(non[0] if len(non) != 0 else "None")

Submission status: Accepted

Solution code:
def slove():
    import sys
    import collections
    input = sys.stdin.readline
    ls = list("abcdefghijklmnopqrstuvwxyz")
    d = collections.defaultdict(int)
    for v in ls:
        d[v]
    s = str(input().rstrip('\n'))
    for i in range(len(s)):
        d[s[i]] = 1
    for k, v in d.items():
        if v == 0:
            print(k)
            exit()
    print("None")


if __name__ == '__main__':
    slove()

Submission status: Accepted

Solution code:
s = set(input())
alpha = set(map(chr, range(97, 123)))

print(sorted(s^alpha)[0] if len(s)!=26 else 'None')

Submission status: Accepted

Solution code:
S=input()
s="abcdefghijklnmopqrstuvwxyz"
s = list(s)
  
for si in S:
  if si in s:
  	s.remove(si)
    
if s == []:
  print("None")
else:
  print(s[0])

Submission status: Accepted

Solution code:
S = input()
s = "abcdefghijklnmopqrstuvwxyz"
s = list(s)

for i in S:
    if i in s:
        s.remove(i)

if s == []:
    print("None")

else:
    print(s[0])

Submission status: Accepted

Solution code:
S=input()
def f(S):
    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 l in L:
        if l not in S:
            return print(l)
    return print("None")
f(S)

Submission status: Accepted

Solution code:
s=input()

x='abcdefghijklmnopqrstuvwxyz'
          
for i in x:
    if i not in s:
        print(i)
        exit()

print('None')

Submission status: Accepted

Solution code:
chars="abcdefghijklmnopqrstuvwxyz"
s=input()
res=None
for i in range(len(chars)):
  if chars[i] not in s:
    res=chars[i]
    break

print(res)

Submission status: Accepted

Solution code:
s = list(input())
s.sort()
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']
no_include = []
sum = 0

for i in alpha:
    if i not in s:
        no_include.append(i)
        sum += 1

if sum != 0:
    print(no_include[0])
else:
    print('None')

Submission status: Accepted

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

Submission status: Accepted

Solution code:
S = 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']
for s in S:
  if s in alpha:
    alpha.remove(s)
if len(alpha) == 0:
  print('None')
else:
  print(alpha[0])

Submission status: Accepted

Solution code:
import string

s=list(set(input()))

for i in list(string.ascii_lowercase):
    if i not in s:
        print(i)
        exit()
print('None')

Submission status: Accepted

Solution code:
S=input()
d={}
for i in range(ord('a'),ord('z')+1):
	d[i]=0
for s in S:
	d[ord(s)]+=1

f=True
for i in d:
	if d[i]==0:
		print(chr(i))
		f=False
		break
if f:print('None')

Submission status: Accepted

Solution code:
s = input()
target = 'None'
for chr_i in range(ord('a'), ord('z')+1):
  if chr(chr_i) not in s:
    target = chr(chr_i)
    break

print(target)

Submission status: Accepted

Solution code:
S=input()
count=[0]*26
c=ord('a')
for s in S:
    count[ord(s)-c]+=1
for i,k in enumerate(count):
    if k == 0:
        print(chr(i+c))
        exit()
print('None')

Submission status: Accepted

Solution code:
a = 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']
if len(set(a))==26:
  print('None')
else:
  for i in range(len(l)):
    if l[i] not in a:
      print(l[i])
      break

Submission status: Accepted

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

a = 'abcdefghijklmnopqrstuvsxyz'

for c in a:
    if c not in s:
        print(c)
        exit(0)

print('None')

Submission status: Accepted

Solution code:
a = set("qwertyuiopasdfghjklzxcvbnm")
s = set(input())
b = a-s
print(sorted(list(b))[0] if len(b) > 0 else "None")

Submission status: Accepted

Solution code:
import sys
S = input()
s_el = set(S)
for a in range(97, 97+26):
    if chr(a) not in s_el:
        print(chr(a))
        sys.exit()
print('None')

Submission status: Accepted

Solution code:
s=input()
alp='abcdefghijklmnopqrstuvwxyz'
for i in range(26):
  alp=[j for j in alp if j not in s]
if len(alp)!=0:
  print(alp[0])
else:
  print('None')

Submission status: Accepted

Solution code:
S = list(input())
T = []

for i in S:
        tmp = ord(i)
        T.append(tmp)

for j in range(ord("a"),ord("z")+1):
        if j not in T:
                print(chr(j))
                exit()

print("None")

Submission status: Accepted

Solution code:
import string
s = input()
l = string.ascii_lowercase
for i in range(len(l)):
    if not (l[i] in s):
        print(l[i])
        exit()
print("None")

Submission status: Accepted

Solution code:
import string
a = set(string.ascii_lowercase)
S = input()
if sorted(list(set(S))) == list(string.ascii_lowercase):
    print("None")
else:
    for i in set(S):
        if i in a:
            a.remove(i)
    print(sorted(list(a))[0])

Submission status: Accepted

Solution code:
s=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']
if len(set(s))==26:
    print('None')
else:
    for i in range(26):
        if l[i] not in s:
            print(l[i])
            break

Submission status: Accepted

Solution code:
s = set(list(input()))
l = set(list('qawsedrfgtyhujikolpzxcvbnm'))
a = list(l-s)
a.sort()
if len(a)==0:
  print('None')
else:
  print(a[0])

Submission status: Accepted

Solution code:
S = set(list(input()))
s = list(S)
c = 'abcdefghijklmnopqrstuvwxyz'

if len(s) == 26:
    print('None')
else:
    for i in c:
        if i not in s:
            print(i)
            exit()

Submission status: Accepted

Solution code:
S = set(list(input()))
s = sorted(list(S))
c = 'abcdefghijklmnopqrstuvwxyz'

if len(s) == 26:
    print('None')
else:
    for i in c:
        if i not in s:
            print(i)
            exit()

Submission status: Accepted

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

# input
S = input()

# solve
flag = False
for i in range(97, 97 + 26):
    if chr(i) not in S:
        ans = chr(i)
        flag = True
        break


# output
print(ans if flag else 'None')

Submission status: Accepted

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

Submission status: Accepted

Solution code:
s = set(list(input()))
t = set(list('qwertyuiopasdfghjklzxcvbnm'))
u = sorted(t-s)
if len(u) == 0:
    print('None')
else:
    print(u[0])

Submission status: Accepted

Solution code:
import string
S = input()
D = {}
for s in S:
  D[s] = 1

for c in string.ascii_lowercase:
  if c not in D:
    print(c)
    exit()
print("None")

Submission status: Accepted

Solution code:
S = input()
set_S = set(list(S))
smallest = ""
for c in list("abcdefghijklmnopqrstuvwxyz"):
    if c not in set_S:
        smallest = c
        break
        
if smallest == "":
    print("None")
else:
    print(smallest)

Submission status: Accepted

Solution code:
import string
s=input()
alp=string.ascii_lowercase
for a in alp:
  if not(a in s):
    print(a)
    exit()
print("None")

Submission status: Accepted

Solution code:
import string
alpha = list(string.ascii_lowercase)
s = input()
li = [st for st in alpha if st not in s]
if len(li) == 0:
    print('None')
elif len(li) > 0:
    print(li[0])

Submission status: Accepted

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


def main():
    S = set(list(input()[:-1]))
    for s in string.ascii_lowercase:
        if s not in S:
            print(s)
            return
    print('None')


if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
s = input()
f = False
for c in 'abcdefghijklmnopqrstuvwxyz':
    if s.find(c) == -1:
        print(c)
        f = True
        break
if f == False:
    print('None')

Submission status: Accepted

Solution code:
s = input()

arr = list(s)

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

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

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

Submission status: Accepted

Solution code:
s = input()
s_sorted = sorted(list(set(s)))
for i in range(97, 97+26):
    if chr(i) not in s_sorted:
        print(chr(i))
        exit()
    else:
        s_sorted.remove(chr(i))
print('None')

Submission status: Accepted

Solution code:
s=list(input())
alpha=[chr(i) for i in range(97, 97+26)]
check=[]
for c in alpha:
    if c not in s:
        check+=[c]
if(check==[]):
    print("None")
else:
    check.sort()
    print(check[0])

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))
        exit()
print('None')

Submission status: Accepted

Solution code:
S = input().lower()
ans = 'None'
for i in range(ord('a'), ord('z')+1):
    if chr(i) not in S:
        ans = chr(i)
        break
print(ans)

Submission status: Accepted

Solution code:
alphabet = 'abcdefghijklmnopqrstuvwxyz'
s = input()
out = None

for i in range(0,len(alphabet)):
  if alphabet[i] not in s:
    out = alphabet[i]
    break
print(out)

Submission status: Accepted

Solution code:
S=list(input())

ans="None"
for t in list("abcdefghijklmnopqrstuvwxyz"):
  if t not in S:
    ans=t
    break
print(ans)

Submission status: Accepted

Solution code:
S=list(input())
T=list("abcdefghijklmnopqrstuvwxyz")

ans="None"
for t in T:
  if t in S:
    1
  else:
    ans=t
    break
print(ans)

Submission status: Accepted

Solution code:
import sys
import math
from fractions import gcd
# import queue
# from collections import Counter
# from itertools import accumulate
# from functools import reduce

def lcm(a, b):
    return a * b // gcd(a, b)

def combination_count(n, r):
    return math.factorial(n) // (math.factorial(n - r) * math.factorial(r))

def permutations_count(n, r):
    return math.factorial(n) // math.factorial(n - r)

big_prime = 1000000007

"""
# 標準入力取得
## 文字列
 = sys.stdin.readline().rstrip()
 = list(sys.stdin.readline().rstrip())

## 数値
 = int(sys.stdin.readline())
 = map(int, sys.stdin.readline().split())
 = list(map(int, sys.stdin.readline().split()))
 = [list(map(int,list(sys.stdin.readline().split()))) for i in range(N)]
"""

alp = "abcdefghijklmnopqrstuvwxyz"
S = sys.stdin.readline().rstrip()

for a in alp:
    if a not in S:
        print(a)
        exit()
print("None")

Submission status: Accepted

Solution code:
s = list(input())
ans ='None'
for i in range(ord('a'),ord('z')+1):
  if (chr(i) not in s):
    ans = chr(i)
    break
print(ans)

Submission status: Accepted

Solution code:
import collections
import string

s = input().rstrip()
counter = collections.Counter()
for c in s:
    counter[c] += 1
for c in string.ascii_lowercase:
    if counter[c] == 0:
        print(c)
        break
else:
    print('None')

Submission status: Accepted

Solution code:
import sys
import string

alphabets = string.ascii_lowercase
s = input()

for i in alphabets:
    if i not in s:
        print(i)
        sys.exit()

print("None")

Submission status: Accepted

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

Submission status: Accepted

Solution code:
import sys

if sys.platform =='ios':
    sys.stdin=open('input_file.txt')


S=input()

Alp="qwertyuiopasdfghjklzxcvbnm"

Q=sorted(set(S)^set(Alp))

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

Submission status: Accepted

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]:
        check_list.append(True)
    else:
        check_list.append(False)

count = 0
for c in check_list:
    if c is True:
        count += 1
    else:
        count += 0

if count == 26:
    print('None')
else:
    print(al_list[count])

Submission status: Accepted

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

ki=[0]*26

for i in range(len(s)):
    for j in range(26):
        if s[i]==al[j]:
            ki[j]+=1
for i in range(26):
    if ki[i]==0:
        print(al[i])
        exit()
print('None')

Submission status: Accepted

Solution code:
S = set(list(input()))
a = {chr(ord('a') + i) for i in range(26)}
d = a - S
print('None' if not len(d) else min(d))

Submission status: Accepted

Solution code:
import string
s = input()
k = string.ascii_letters
alist = [0]*26
for i in s:
    alist[ord(i)-ord("a")] = 1
c = -1
for i in range(26):
    if alist[i] == 0:
        c = i
        break    
if c == -1:
    print("None")
else:
    print(k[c])

Submission status: Accepted

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

Submission status: Accepted

Solution code:
import string
S = set([c for c in input()])
for c in string.ascii_lowercase:
    if c not in S:
        print(c)
        exit()
print("None")

Submission status: Accepted

Solution code:
S = input()
d = {}
for s in S:
    d[s] = 1
a = [chr(i) for i in range(97, 97+26)]
ans = "None"
for i in a:
    if not i in S:
        ans = i
        break
print(ans)

Submission status: Accepted

Solution code:
def resolve():
    s = input()
    t = set([c for c in "abcdefghijklmnopqrstuvwxyz"])
    st = sorted(set(t) - set(s))
    print(st[0] if st else "None")


if __name__ == "__main__":
    resolve()

Submission status: Accepted

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: Accepted

Solution code:
S = input()
S_list = list(set(S))
string = "qazwsxedcrfvtgbyhnujmikolp"
str_list = list(string)
str_list.sort()
for a in S_list:
    str_list.remove(a)
if str_list == []:
    print("None")
else:
    print(str_list.pop(0))

Submission status: Accepted

Solution code:
import string

a_z = set(string.ascii_lowercase)

s = set(input())

subtract_alphabet = list(a_z - s)
if len(subtract_alphabet) == 0:
    print("None")
else:
    print(min(subtract_alphabet))

Submission status: Accepted

Solution code:
import string
S = input()
eigo = string.ascii_lowercase
eigo_list = list(eigo)

count = 0

for x in eigo_list:
    if not  x in S:
        print(x)
        count += 1
        break
    
if count == 0:
    print("None")

Submission status: Accepted

Solution code:
from collections import deque
char = deque(['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'])

string = list(input())

for i in range(len(string)):
    if string[i] in char:
        char.remove(string[i])

output = char.popleft() if char else "None"
print(output)

Submission status: Accepted

Solution code:
s = list(input())

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

print (r)

Submission status: Accepted

Solution code:
S = set(list(input()))
A = "abcdefghijklmnopqrstuvwxyz"

for i in A:
    if i not in S:
        print(i)
        break
else:
    print("None")

Submission status: Accepted

Solution code:
A = ['a','s','d','f','g','h','j','k','l','z','x','c','v','b','n','m','q','w','e','r','t','y','u','i','o','p']
S = list(set(input()))
for i in S:
    A.remove(i)
A.sort()
try:
    print(A[0])
except:
    print("None")

Submission status: Accepted

Solution code:
tester = "abcdefghijklmnopqrstuvwxyz"
s = input()
ans = "None"
for i in range(len(tester)):
    if s.count(tester[i]) == 0:
        ans = tester[i]
        break
print(ans)

Submission status: Accepted

Solution code:
S = input()

import string

letters = string.ascii_lowercase

S = set(sorted(S))
for l in letters:
    if l not in S:
        print(l)
        break

else:
    print("None")

Submission status: Accepted

Solution code:
s = input()
abcList = "abcdefghijklmnopqrstuvwxyz"
swi = "None"
for i in range(len(abcList)):
    if s.count(abcList[i]) == 0:
        swi = abcList[i]
        break
print(swi)

Submission status: Accepted

Solution code:
import string


s = input()
t = set(s)
for ch in sorted(string.ascii_lowercase):
    if not ch in t:
        print(ch)
        exit(0)

print('None')

Submission status: Accepted

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

Submission status: Accepted

Solution code:
S = list(input())

S_set = set(S)

ABC = set(list('abcdefghijklmnopqrstuvwxyz'))

A = ABC - S_set
if len(A)==0:print('None')
else:
    A = list(A)
    A.sort()
    print(A[0])

Submission status: Accepted

Solution code:
original = 'abcdefghijklmnopqrstuvwxyz'
s = input()
for i in range(len(s)):
    if s[i] in original:
        original = original.replace(s[i], '')
if len(original) > 0:
    print(original[0])
else:
    print(None)

Submission status: Accepted

Solution code:
import numpy as np

S = input()

S = np.unique(sorted(S))

ans = 'None'
for ch in 'abcdefghijklmnopqrstuvwxyz':
  if ch in S:
    pass
  else:
    ans = ch
    break
print(ans)

Submission status: Accepted

Solution code:
S=input()
for i in range(97,123):
 c=chr(i)
 if c not in S:print(c);quit()
print(None)

Submission status: Accepted

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

Submission status: Accepted

Solution code:
s = input()
alp = "abcdefghijklmnopqrstuvwxyz"
for i in s:
  alp = alp.replace(i, "")

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