Problem:
Score : 300 points

Problem Statement

1000000000000001 dogs suddenly appeared under the roof of Roger's house, all of which he decided to keep. The dogs had been numbered 1 through 1000000000000001, but he gave them new names, as follows:

the dogs numbered 1,2,\cdots,26 were respectively given the names a, b, ..., z;

the dogs numbered 27,28,29,\cdots,701,702 were respectively given the names aa, ab, ac, ..., zy, zz;

the dogs numbered 703,704,705,\cdots,18277,18278 were respectively given the names aaa, aab, aac, ..., zzy, zzz;

the dogs numbered 18279,18280,18281,\cdots,475253,475254 were respectively given the names aaaa, aaab, aaac, ..., zzzy, zzzz;

the dogs numbered 475255,475256,\cdots were respectively given the names aaaaa, aaaab, ...;

and so on.

To sum it up, the dogs numbered 1, 2, \cdots were respectively given the following names:

a, b, ..., z, aa, ab, ..., az, ba, bb, ..., bz, ..., za, zb, ..., zz, aaa, aab, ..., aaz, aba, abb, ..., abz, ..., zzz, aaaa, ...

Now, Roger asks you:

"What is the name for the dog numbered N?"

Constraints

N is an integer.

1 \leq N \leq 1000000000000001

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer to Roger's question as a string consisting of lowercase English letters.

Sample Input 1

2

Sample Output 1

b

Sample Input 2

27

Sample Output 2

aa

Sample Input 3

123456789

Sample Output 3

jjddja

Solution in Python (3.8.2) (judge verdict: Accepted)

N = int(input())

#26の倍数の辞書を保持する

a = 1
baisu = []
ruiseki = [26]

for i in range(11):
    a *= 26
    baisu.append(a)
    if i != 0:
        ruiseki.append(ruiseki[i-1]+a)

#何桁か  
length = 0
new_N = 0
f = True
for i,rui in enumerate(ruiseki):
    if N <= rui:
        length = i+1
        if i!=0:
            new_N = N-ruiseki[i-1]
        else:
            new_N = N
        f = False
        break
if f:
    new_N = N-ruiseki[-1]

# print(length)



# print(new_N)
# print(length)
# print(baisu)

ans = []
for i in range(length):
    u = 0
    cnt = 0
    while(1):
        if new_N <= 26 and i==length-1:
            ans.append(new_N-1)

            break
        pre_u = u
        u += baisu[length - i -2 ]
        if new_N <= u:
            ans.append(cnt)
            new_N -= pre_u
            break
        cnt += 1

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

# print(ans)
for an in ans:
    ans_c+=alp[an]
print(ans_c)




# while(1):
#     for bai in baisu:


# print(baisu)
# print(ruiseki)