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:
word = input()
alphabet = [chr(i) for i in range(97,97+26)]

none_alpha = ["None"]

for i in range(26):
    if alphabet[i] in none_alpha:
        continue;
    a = word.find(alphabet[i])
    if a == -1:
        if "None" in none_alpha:
            none_alpha.remove("None")
        none_alpha.append(alphabet[i])

print(none_alpha[0])

Submission status: Accepted

Solution code:
S = list(input())

alphabets = ["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"]

i = 0
while i in range(len(alphabets)):
    if alphabets[i] in S:
        i += 1
    else:
        print(alphabets[i])
        break
else:
    print ("None")

Submission status: Accepted

Solution code:
import string

s = input()
alp = string.ascii_lowercase

def search(s, c):
    for i in s:
        if i == c:
            return 1
    return 0

f = 0
for i in alp:
    if not search(s, i):
        print (i)
        f = 1
        break;
if not f:
    print ("None")

Submission status: Accepted

Solution code:
s = input()

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

flag = [False for i in range(26)]

for c in s:
    flag[ord(c) - ord("a")] = True


def pr():
    for i in range(26):
        if not flag[i]:
            print(alp[i])
            return

    print('None')
    return

pr()

Submission status: Accepted

Solution code:
S = input()
ls = [chr(i) for i in range(ord("a"),ord("z")+1)]
for c in S:
    if c in ls:
        ls.remove(c)
if ls==[]:
    print("None")
else:
    print(ls[0])

Submission status: Accepted

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

Submission status: Accepted

Solution code:
S = set(input())          

X = set('abcdefghijklmnopqrstuvwxyz')               

S=X-S                     

print("None" if S==set() else min(S))

Submission status: Accepted

Solution code:
import string
s = list(input())
a = list(string.ascii_lowercase)
l = []
for index, i in enumerate(a):
    if i not in s:
        print(i)
        break
else:
    print(None)

Submission status: Accepted

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

if __name__ == "__main__":
    main()

Submission status: Accepted

Solution code:
# -*- coding:utf-8 -*-
a = list('abcdefghijklmnopqrstuvwxyz')
S = list(input())
b = list(set(S))
for tmp in b:
    a.pop(a.index(tmp))
if len(a) == 0:
    print("None")
else:
    print(a.pop(0))

Submission status: Accepted

Solution code:
import string

S = input()

X = set(string.ascii_lowercase) - set(S)
if X:
    print(sorted(list(X))[0])
else:
    print(None)

Submission status: Accepted

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

Submission status: Accepted

Solution code:
s=input()
ans="None"
import string
for i in string.ascii_lowercase:
    if i not in s:
        ans=i
        break
print(ans)

Submission status: Accepted

Solution code:
s=input()
a=ord('a')
z=ord('z')
flag=False
for i in range(a,z+1):
    c=chr(i)
    if not c in s:
        flag=True
        print(c)
        break

if not flag:
    print('None')

Submission status: Accepted

Solution code:
s = raw_input()
for i in range(26):
    c = chr(ord('a')+i)
    if c in s:
        continue
    else:
        print c
        break
else:
    print 'None'

Submission status: Accepted

Solution code:
#ABC071B
import sys

s=raw_input()
l=[False for i in xrange(26)]
for i in xrange(len(s)):
 temp=ord(s[i])-97
 l[temp]=True
if len(set(s))==26:
 print 'None'
 sys.exit()
for i in xrange(26):
 if not l[i]:
  print chr(i+97)
  break

Submission status: Accepted

Solution code:
S = input()
ans = None
for letter in "abcdefghijklmnopqrstuvwxyz":
    if letter not in S:
        ans = letter
        break
print(ans)

Submission status: Accepted

Solution code:
import string


def main():
    s = input()
    for c in string.ascii_lowercase:
        if c not in s:
            print(c)
            break
    else:
        print("None")

if __name__ == "__main__":
    main()

Submission status: Accepted

Solution code:
import string

a = input()

f = False
for i in string.ascii_lowercase:
    if i not in a:
        print(i)
        f = True
        break

if not f:
    print("None")

Submission status: Accepted

Solution code:
import string
import sys
from collections import Counter

# sys.stdin = open('b1.in')


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


def read_str_list():
    return input().split()


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


def read_str():
    return input()


def main():
    a = list(string.ascii_lowercase)
    res = None
    s = read_str_list()
    l = list(s)
    l.sort()
    s = ''.join(l)

    c = Counter(s)
    for i in a:
        if c[i] == 0:
            res = i
            break

    print(res)


main()

Submission status: Accepted

Solution code:
s = list(input())
d = {}
for c in s:
    d[c] = True
ans = "None"
for i in range(26):
    c = chr(ord('a') + i)
    if c not in d:
        ans = c
        break

print(ans)

Submission status: Accepted

Solution code:
s=raw_input()
a=[0 for i in range(26)]
p=-1
for i in range(len(s)):
    a[ord(s[i])-97]=1
for i in range(26):
    if a[i]==0:
        print chr(i+97)
        exit()
print "None"

Submission status: Accepted

Solution code:
S = set(map(ord,input()))
alphabet = set(map(ord,'abcdefghijklmnopqrstuvwxyz'))

x = alphabet - S
try:
    print(chr(min(x)))
except:
    print('None')

Submission status: Accepted

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

Submission status: Accepted

Solution code:
s=input()
char=['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']
check=False
for c in char:
    if not c in s:
        print(c,end='')
        check=True
        break
if  check==False:
    print('None',end='')

Submission status: Accepted

Solution code:
S = str(input())
list_S = []

for i in range(len(S)):

    list_S.append(S[i:i+1])



alf = 'abcdefghijklmnopqrstuvwxyz'
list_alf = []
for i in range(len(alf)):
    list_alf.append(alf[i:i+1])

count = 0
conti = 0

for i in range(len(alf)):
    count = list_S.count(list_alf[i])
    if count == 0:
        print (list_alf[i])
        break
    conti += 1


if conti >= 26:
    print ('None')

Submission status: Accepted

Solution code:
myinput=input()
for c in 'abcdefghijklmnopqrstuvwxyz':
    if c not in myinput:
        print(c)
        break
else:
    print('None')

Submission status: Accepted

Solution code:
st = input()
hash_set = set()
for item in st:
    hash_set.add(item)

a = "abcdefghijklmnopqrstuvwxyz"

flag = False
for item in a:
    if not item in hash_set:
        print(item)
        flag = True
        break

if flag == False:
    print("None")

Submission status: Accepted

Solution code:
S = str(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']

n = 0

for i in range(26):

	if alpha[n] not in S:
		print(alpha[n])
		break
	if n == 25:
		print("None")
		break
		
	n += 1

Submission status: Accepted

Solution code:
S = raw_input()
ss = set(S)
ans = set("abcdefghijklmnopqrstuvwxyz").difference(ss)

if len(ans): print(min(ans))
else: print("None")

Submission status: Accepted

Solution code:
s = input()
s_list = list(s)
s_set = set(s_list)
abc_list = [chr(i) for i in range(97, 97+26)]
if len(s_set) == 26:
    print("None")
else:
    for a in abc_list:
        if a in s_set:
            pass
        else:
            print(a)
            break

Submission status: Accepted

Solution code:
S=input()
check=True
 
for i in range(0,26):
    if S.find(chr(i+97))==-1:
        print(chr(i+97))
        check=False
        break


print("None" if check else "")

Submission status: Accepted

Solution code:
a = input()

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

flag = True;
for c in alpha:
    if c not in a:
        print(c)
        flag = False
        break

if flag:
    print("None")

Submission status: Accepted

Solution code:
S = input()
countList = []
alphabetList = []
for i in range(ord("a"),ord("z")+1):
    alphabetList.append(chr(i))
    countList.append(S.count(chr(i)))
if min(countList) != 0:
    print("None")
else:
    print(alphabetList[countList.index(0)])

Submission status: Accepted

Solution code:

s=input()
s=list(s)
nums=[]
for i in s: nums.append(ord(i))

flag=True
for i in range(97,123):
    if i in nums: pass
    else: print(chr(i));flag=False; break
if flag: print("None")

Submission status: Accepted

Solution code:
S = input()
l = set(list(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'} - l
l = list(l)
l.sort()
print(l[0] if(len(l)) else "None" )

Submission status: Accepted

Solution code:
st = list(input())
ls = list(set(st))
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']
set_ab = set(abc) - set(ls)
ans = list(set_ab)
ans.sort()
if ans:
    print(ans[0])
else:
    print("None")

Submission status: Accepted

Solution code:
S = input()
x = [chr(i) for i in range(ord("a"),ord("z")+1)]
for i in x:
  if i not in S:
    print(i)
    break
  if i == x[-1]:
    print("None")
    break

Submission status: Accepted

Solution code:
def b():
    alphabets = 'abcdefghijklmnopqrstuvwxyz'
    s = input()
    # print(set(alphabets), set(s))
    diff = set(alphabets) - set(s)
    try:
        print( sorted(list(diff))[0] )
    except:
        print('None')

b()

Submission status: Accepted

Solution code:
import math
def search(x,n):
	curPos=0
	log2=int(math.log(n,2))
	newPos=0
	if s[curPos]==x:
		return True
	while log2 >=0:
		newPos=curPos + (1 << log2)
		if newPos < n and s[newPos]<=x:
			curPos=newPos
		if s[curPos]==x:
			return True
		log2-=1
	return False

s=input()
s=list(s)
s.sort()
n=len(s)
s_str=[chr(x) for x in range(97,123)]
Found=False
for i in s_str:
	res=search(i,n)
	if not res:
		print(i)
		Found=True
		break
if not Found:
	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"]
S = list(set(S))
S.sort()
#print(len(S))
for i in range(len(S)):
    if S[i] != alpha[i]:
        print(alpha[i])
        break
    elif i == 25:
        print("None")
    elif i == len(S) - 1:
        print(alpha[i+1])

Submission status: Accepted

Solution code:
from collections import Counter
S = input()

counter = dict(Counter(S))
counter = sorted(counter) 
alphabets = "abcdefghijklmnopqrstuvwxyz"

found = False
for letter in alphabets:
    if letter in counter:
        continue
    else:
        found = True
        print(letter)
        break

if found is not True:
    print("None")

Submission status: Accepted

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

Submission status: Accepted

Solution code:
string=input()
l="abcdefghijklmnopqrstuvwxyz"
for i in l:
    if i not in string:
        print(i)
        break
else:
    print("None")

Submission status: Accepted

Solution code:
letters = [chr(i) for i in range(97,123)]
string  = input()
for j in range(len(string)):
    if string[j] in letters:
        letters.remove(string[j])
    else:
        continue
if letters:
    print(letters[0])
else:
    print("None")

Submission status: Accepted

Solution code:

S=map(str,raw_input())
S.sort()
flag=1
SS=[]
for i in S:
    SS.append(ord(i))
for i in range(ord("a"),ord("z")+1):
    if not i in SS:
        ans=chr(i)
        print ans
        flag=0
        break
if flag==1:
    print "None"

Submission status: Accepted

Solution code:
def main():
    S = input()
    alphabet = "abcdefghijklmnopqrstuvwxyz"
    #print(alphabet)
    #com = S + alphabet
    #print(sorted(set(com), key=com.index))
    dic = str.maketrans("", "", S)
    ans = alphabet.translate(dic)
    if(len(ans) > 0):
        print(ans[0])
    else:
        print("None")
    
    
if __name__=="__main__":
    main()

Submission status: Accepted

Solution code:
word_list = list(input().lower())
alphabet_uniq = list(set(word_list))
alphabet_uniq.sort()

alphabet_uniq.append('END')
if len(alphabet_uniq) != 27:
    for i in range(0, len(alphabet_uniq)):
        if chr(i + 97) != alphabet_uniq[i]:
            print(chr(i + 97))
            break
else:
    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']

for c in s:
    if c in a:
        a.remove(c)
if len(a) > 0:
    print(a[0])
else:
    print("None")

Submission status: Accepted

Solution code:
x = str(input())

for i in range(97,123):
    if(x.find(chr(i))==-1):
        print(chr(i))
        quit()

print('None')


quit()

Submission status: Accepted

Solution code:
a = raw_input().strip()
al = 'abcdefghijklmnopqrstuvwxyz'
for x in al:
	try:
		i = a.index(x)
	except :
		print(x)
		exit()
print('None')

Submission status: Accepted

Solution code:
import sys

DICT = ['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 = set(DICT)
s = set(list(sys.stdin.readline().strip()))

z = sorted(list(d-s))

if len(z) >= 1:
    print(z[0])
else:
    print('None')

Submission status: Accepted

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

S = input()
CHR = [chr(i) for i in range(97, 97+26)]

judge = 1
i = 0

while(judge > 0 and i <= 25):
    judge = S.count(CHR[i])
    i = i+1

if(judge==0):
    print(CHR[i-1])
else:
    print("None")

Submission status: Accepted

Solution code:
s = input()

l = list(s)
#l=list(set(l))
#l.sort()
#print(l)

l_abc = list("abcdefghijklmnopqrstuvwxyz")

l = list(set(l_abc) - set(l))
l.sort()

#print(l)
#print(len(l))

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

Submission status: Accepted

Solution code:
string = ['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 =[d for d in input()]
find = 0
i=0
found = False
while i<26 and not found:
    if string[i] in s :
        found= False
    else:
        find =string[i]
        found=True
    i +=1

if found:
    print(find)
else:
    print('None')

Submission status: Accepted

Solution code:
import sys
S = input()
a = 'abcdefghijklmnopqrstuvwxyz'
a = 'abcdefghijklmnopqrstuvwxyz'
for aa in a:
    if aa in S:
        pass
    else:
        print(aa)
        sys.exit()
print('None')

Submission status: Accepted

Solution code:
S = input()

X = 'abcdefghijklmnopqrstuvwxyz'

for x in X:
    if x not in S:
        print(x)
        exit()

print('None')

Submission status: Accepted

Solution code:
if __name__ == '__main__':
    char = list('abcdefghijklmnopqrstuvwxyz')
    S = input()
    for i in range(len(S)):
        if S[i:i+1] in char:
            char.remove(S[i:i+1])
    if len(char) == 0:
        print('None')
    else:
        print(char[0])

Submission status: Accepted

Solution code:
abc='abcdefghijklmnopqrstuvwxyz'
s=raw_input().strip()
isi=set()
for l in s:
    if l not in isi:
        isi.add(l)
for l in abc:
    if l not in isi:
        print l
        break
else:
    print 'None'

Submission status: Accepted

Solution code:
s2 = "abcdefghijklmnopqrstuvwxyz"
s2 = set(s2)
s = set(raw_input())
if len(s) == 26:
    print "None"
a = list(s2 -s)
if len(a) >0:
  a.sort()
  print a[0]

Submission status: Accepted

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

Submission status: Accepted

Solution code:
import sys
S=list(raw_input())
#print S
#print len(S)

A=list('abcdefghijklmnopqrstuvwxyz')

#print A


for i in range(len(A)):
	#print "A[i]:::"+str(A[i])
	for cnt,v in enumerate(S):
		#print A[i]
		#print cnt,v
		if A[i]==v:
			if A[i]=='z':
				print 'None'
				break
			else:
				break
		if cnt==len(S)-1:
			print A[i]
			sys.exit()

Submission status: Accepted

Solution code:
s = list(set(input()))
abc = "abcdefghijklmnopqrstuvwxyz"
s.sort()
if len(s)==26: print("None")
else:
  for a in abc:
    if not(a in s):
      print(a)
      break

Submission status: Accepted

Solution code:
alphabet_list = [0 for x in range(ord('a'),ord('z')+1)]

S = list(raw_input())

for x in S:
    alphabet_list[ord(x) - ord('a')] += 1

print_flag = False
for index in range(0,ord('z')-ord('a')+1):
    if alphabet_list[index] == 0:
        print(chr(index+ord('a')))
        print_flag = True
        break

if not(print_flag):
    print('None')

Submission status: Accepted

Solution code:
a_list=("abcdefghijklmnopqrstuvwxyz")
word=(raw_input())
flag=0
out="None"
for i in a_list:
    for n,k in enumerate(word):
        if i==k:
            break
        if n==len(word)-1:
            out=i
            flag=1
    if flag==1:
        break
print(out)

Submission status: Accepted

Solution code:
def B_NotFound(lst):
    comparison = 'abcdefghijklmnopqrstuvwxyz'
    lst = sorted(set(lst))  # 文字列をソート(重複はいらないので除く)

    string = [''] * len(comparison)
    for i in range(len(lst)):
        string[i] = lst[i]

    for i in range(len(string)):
        if string[i] != comparison[i]:
            return comparison[i]
    return 'None'

s = input()
print(B_NotFound(s))

Submission status: Accepted

Solution code:
def search(code):
    for i in range(len(code)):
        if code[i] == 0:
            return i
    else:
        return -1

s = raw_input()

code = [0 for i in range(26)]

for i in range(len(s)):
    key = ord(s[i]) - 97
    code[key] += 1

rt = search(code)

if rt >= 0:
    print chr(rt + 97)
else:
    print "None"

Submission status: Accepted

Solution code:
s = input()
arr = "abcdefghijklmnopqrstuvwxyz"
ans = []
for word in arr:
    if word in s:
        pass
    else:
        ans.append(word)
if len(ans) == 0:
    print("None")
else:
    print(ans[0])

Submission status: Accepted

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

[dic.remove(c) for c in charset]
if dic == []:
    print("None")
else:
    print(dic[0])

Submission status: Accepted

Solution code:
S = input()
d = {}

for i in range(ord("a"), ord("z") + 1):
    d[chr(i)] = False

for c in S:
    d[c] = True

ans = "None"
for i in range(ord("a"), ord("z") + 1):
    if not d[chr(i)]:
        ans = chr(i)
        break
print(ans)

Submission status: Accepted

Solution code:
#from time import time
#t = time()
n = input()
d=[]
abc =[chr(x) for x in range(97, 123)]
for i in abc:
    if i not in  n:
        d.append(i)
if d != []:
    print(sorted(d)[0])
else:
    print('None')

#print(mn[0] * mm[1])
#tt= time()
#print(tt-t)

Submission status: Accepted

Solution code:
a = input()
b = ["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"]
i = 0
while len(a) > i:
    if a[i] in b:
        b.remove(a[i])
    else:
        pass
    i += 1
if not b:
    print("None")
else:
    print(b[0])

Submission status: Accepted

Solution code:
def main():
    s = set(list(input()))
    check = list("qwertyuiopasdfghjklzxcvbnm")
    check.sort()
    for i in check:
        if i not in s:
            print(i)
            return
    print("None")

main()

Submission status: Accepted

Solution code:
s = input()
count =[0 for i in range(26)]

for i in s:
    count[ord(i)-ord("a")]+=1


for i in range(len(count)):
    if count[i] == 0:
        print(chr(i+ord("a")))
        break
else:
    print("None")

Submission status: Accepted

Solution code:
# coding=utf-8
S = list(raw_input())

alpha = 'abcdefghijklmnopqrstuvwxyz'
t = True
for a in alpha:
    if a not in S:
        print a
        t = False
        break
if t:
    print None

Submission status: Accepted

Solution code:
S = input()
alf = "abcdefghijklmnopqrstuvwxyz"
li = []

for x in alf:
    if (x in S) == False:
      li.append(x)
      break

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

Submission status: Accepted

Solution code:
s = input()
ab_list = [True]*26
for i in s:
  ab_list[ord(i)-97] = False
for i in range(len(ab_list)):
  if ab_list[i]:
    print(chr(i+97))
    exit()
print("None")

Submission status: Accepted

Solution code:
S=input()

sorted(S)

if 'a' not in S:
    print('a')
elif 'b' not in S:
    print('b')
elif 'c' not in S:
    print('c')
elif 'd' not in S:
    print('d')
elif 'e' not in S:
    print('e')
elif 'f' not in S:
    print('f')
elif 'g' not in S:
    print('g')
elif 'h' not in S:
    print('h')
elif 'i' not in S:
    print('i')
elif 'j' not in S:
    print('j')
elif 'k' not in S:
    print('k')
elif 'l' not in S:
    print('l')
elif 'm' not in S:
    print('m')
elif 'n' not in S:
    print('n')
elif 'o' not in S:
    print('o')
elif 'p' not in S:
    print('p')
elif 'q' not in S:
    print('q')
elif 'r' not in S:
    print('r')
elif 's' not in S:
    print('s')
elif 't' not in S:
    print('t')
elif 'u' not in S:
    print('u')
elif 'v' not in S:
    print('v')
elif 'w' not in S:
    print('w')
elif 'x' not in S:
    print('x')
elif 'y' not in S:
    print('y')
elif 'z' not in S:
    print('z')
else:
    print('None')

Submission status: Accepted

Solution code:
#! -*- coding:utf-8 -*-
s = str(input())
s = list(s)
x = 'abcdefghijklmnopqrstuvwxyz'
x = list(x)

flag = 0
for i in range(len(s)):
    try:
        if(len(x) == 1 and s[i] == x[0]):
            flag = 1
        x.remove(s[i])
    except:
        pass

if(flag == 1):
    print('None')
else:
    print(x[0])

Submission status: Accepted

Solution code:
hoge = [0] * 26
a = ord('a')
string = input()
for i in range(len(string)):
    hoge[ord(string[i])-a] = 1

for i in range(26):
    if hoge[i] == 0:
        print(chr(i+a))
        break
    if i == 25:
        print('None')

Submission status: Accepted

Solution code:
d = raw_input()

d_list = []
for i in range(len(d)):
    d_list.append(ord(d[i]))

ans = ord('a')
while True:
    if ans not in d_list:
        break
    if ans > ord('a')+122:
        break
    ans += 1

if ans > 122:
    print 'None'
else:
    print chr(ans)

Submission status: Accepted

Solution code:
import string


def main():
    S = input()
    _str = set(S)
    lower_set = set(string.ascii_lowercase)
    if _str == lower_set:
        print("None")
    else:
        no_exists = list(lower_set - _str)
        print(sorted(no_exists)[0])


if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
import string

S = str(input())

a = set(S)
b = set(string.ascii_lowercase)
c = b - a
if len(list(c)) == 0:
    print(None)
else:
    print(sorted(list(c))[0])

Submission status: Accepted

Solution code:
def main():
    S = input()

    for i in range(97, 123):
        if not chr(i) in S:
            ans = chr(i)
            break
    else:
        ans = 'None'

    print(ans)

main()

Submission status: Accepted

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

for c in L:
    if c in S:
        if c == 'z':
            print('None')
        continue
    else:
        print(c)
        break

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"]

ans = ""
for i in range(len(S)):
    if S[i] in alphabet:
        alphabet.remove(S[i])
        if len(alphabet) == 0:
            break

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

Submission status: Accepted

Solution code:
#!usr/bim/python
#! -*- coding: utf-8 -*-

import re

alphabet = 'abcdefghijklmnopqrstuvwxyz'

s = raw_input()

status = len(alphabet)

for i in range(len(alphabet)):
    if not re.search(alphabet[i],s):
        status = i
        break

if status == len(alphabet):
    print 'None'
else:
    print alphabet[status]

Submission status: Accepted

Solution code:
s = str(raw_input())
alphabets, result = "abcdefghijklmnopqrstuvwxyz", "None"
for i in range(26):
    if alphabets[i] not in s:
        result = alphabets[i]
        break
print(result)

Submission status: Accepted

Solution code:
s = input().strip()

alphabets = 'abcdefghijklmnopqrstuvwxyz'

s_set = set(s)

for c in alphabets:
    if c not in s_set:
        print(c)
        exit()
print('None')

Submission status: Accepted

Solution code:
#coding=UTF-8

S=input()
ans='None'
for chr_num in range(ord('a'),ord('z')+1,1):
    mozi=chr(chr_num)
    if not(mozi in S):
        ans=mozi
        break

print(ans)

Submission status: Accepted

Solution code:
import string
s = list(input())
flag = 0

for a in string.ascii_lowercase:
    if a not in s:
        print(a)
        flag = 1
        break

if flag == 0:
    print("None")

Submission status: Accepted

Solution code:
S=set(input())
k=0
for i in range(97, 97+26):
    s0=set(chr(i))
    if(not(s0.issubset(S)) and k==0):
        k=chr(i)
        break
    
if(k!=0):
    print(k)
else:
    print("None")

Submission status: Accepted

Solution code:
S = list(input())

T = list('abcdefghijklmnopqrstuvwxyz')

sub = [c for c in T if c not in S]
if len(sub) != 0:
    print(sub[0])
else:
    print('None')

Submission status: Accepted

Solution code:
import sys
inp = lambda t: t(sys.stdin.readline().strip())
inpm = lambda t: map(t, sys.stdin.readline().split())
inpl = lambda t: list(map(t, sys.stdin.readline().split()))

s = inp(str)

p = set()
for i in s:
	if i not in p:
		p.add(i)

for i in range(ord('a'), ord('z') + 1):
	if chr(i) not in p:
		print(chr(i))
		break
else:
	print('None')

Submission status: Accepted

Solution code:
S = input()

for i in "abcdefghijklmnopqrstuvwxyz":
    if S.replace(i,"") == S:
        print(i)
        break
else:
    print("None")

Submission status: Accepted

Solution code:
# coding: utf-8
txt = input()
for c in 'abcdefghijklmnopqrstuvwxyz':
    if c not in txt:
        print(c)
        break
else:
    print('None')

Submission status: Accepted

Solution code:
import string

standard_let = string.ascii_lowercase

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

Submission status: Accepted

Solution code:
s=set(raw_input())
res = 'None'
for i in 'abcdefghijklmnopqrstuvwxyz' :
    if i not in s :
        res = i
        break
print res

Submission status: Accepted

Solution code:
#Not Found
s = list(input())

c = [chr(i) for i in range(97, 97+26)]
ans = "None"
for ci in c:
    if( ci not in list(s) ):
        ans = ci
        break
print(ans)

Submission status: Accepted

Solution code:
s = set(input())
alp = set('abcdefghijiklmnopqrstuvwxyz')
try:
	print(sorted(list(alp - s))[0])
except:
	print('None')

Submission status: Accepted

Solution code:
# -*- coding: utf-8 -*-
s = input()

import sys

N = 26

ary = [False for i in range(N)]

for a in s:
    ary[ord(a) - ord('a')] = True
for i, a in enumerate(ary):
    if not a:
        print(chr(i + ord('a')))
        sys.exit()

print("None")

Submission status: Accepted

Solution code:
string=raw_input()
allist=['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']
ans='None'
for i in range(len(allist)):
    if allist[i] not in string:
        ans=allist[i]
        break
print ans

Submission status: Accepted

Solution code:
import string
S = input()
diff = set(string.ascii_lowercase) - set(S)
diff = sorted(list(diff))
if len(diff) == 0:
    print('None')
else:
    print(diff[0])

Submission status: Accepted

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

for i in alph:
    if i not in s:
        print(i)
        break
    if i=='z':
        print("None")

Submission status: Accepted

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

a=list('abcdefghijklmnopqrstuvwxyz')

for i in a:
    if i not in S:
        print(i)
        exit()
else:
    print('None')

Submission status: Accepted

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

Submission status: Accepted

Solution code:



def main():
    s = input()
    chars = set(s)

    for i in range(ord('a'), ord('z')+1):
        if chr(i) not in chars:
            print(chr(i))
            break
    else:
        print('None')


if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:


s = input()
s = set(list(s))

ans = 'None'

for alpha in list('abcdefghijklmnopqrstuvwxyz'):
    if alpha not in s:
        ans = alpha
        break

print(ans)

Submission status: Runtime Error

Solution code:
s=input()
a='abcdefghijklmnopqrstuvwxyz'
for S in s:    
    for i in (len(a)):
        if S in a:
            continue
        else:
            print(a[i])
            exit()
print('None')

Submission status: Runtime Error

Solution code:
import sys
S = list(input())
s = list(set(S))
s.sort()
alfa = list('abcdefghijklmnopqrstuvwxyg')
ans = 0
if(len(s)==len(alfa)):
  print('None')
  sys.exit()
else:
  for i in range(len(s)):
    if(s[i]!=alfa[i]):
      print(alfa[i])
      sys.exit()
  print(alfa[len(s)+1])

Submission status: Runtime Error

Solution code:
import sys
S = list(input())
s = list(set(S))
s.sort()
alfa = list('abcdefghijklmnopqrstuvwxyg')
ans = 0
if(len(s)==len(alfa)):
  print('None')
else:
  for i in range(len(s)):
    if(s[i]!=alfa[i]):
      print(alfa[i])
      sys.exit()
  print(a)

Submission status: Runtime Error

Solution code:
s = input()
r = set(map(chr, range(97, 97+26)))
r = r - set(s)
r = min(r)
print(r)

Submission status: Runtime Error

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

alphabet = list('abcdefghijklmnopqrstuvwxyz')

if alphabet == S:
    print('None')
    exit()
elif len(S) == 1 and S[0] == 'a':
    print('b')
    exit()

for i in range(len(alphabet)):
    if S[i] == alphabet[i]:
        continue
    else:
        print(alphabet[i])
        exit()

Submission status: Runtime Error

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

alphabet = list('abcdefghijklmnopqrstuvwxyz')

if alphabet == S:
    print('None')
    exit()

for i in range(len(alphabet)):
    if S[i] == alphabet[i]:
        continue
    else:
        print(alphabet[i])
        exit()