Problem: 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?"

Submission attempts (in order):
import numpy as np
import scipy.sparse as sps
import scipy.misc as spm
import collections as col
import functools as func
import itertools as ite
import fractions as frac
import math as ma
from math import cos,sin,tan,sqrt
import cmath as cma
import copy as cp
import sys
import re
import bisect as bs
sys.setrecursionlimit(10**7)
EPS = sys.float_info.epsilon
PI = np.pi; EXP = np.e; INF = np.inf
MOD = 10**9 + 7

def sinput(): return sys.stdin.readline().strip()
def iinput(): return int(sinput())
def imap(): return map(int, sinput().split())
def fmap(): return map(float, sinput().split())
def iarr(n=0):
    if n: return [0 for _ in range(n)]
    else: return list(imap())
def farr(): return list(fmap())
def sarr(n=0):
    if n: return ["" for _ in range(n)]
    else: return sinput().split()
def barr(n): return [False for _ in range(n)]
def adj(n): return [[] for _ in range(n)]

n = iinput()
ch = ["z"]+[chr(i) for i in range(ord("a"), ord("a")+25)]

def cnt26(num):
    cnt = 0
    while 1:
        if 26 ** cnt > num: return cnt - 1
        else: cnt += 1

s = ""
dig = cnt26(n)
while dig >= 1:
    div,mod = divmod(n, 26**dig)
    #print(div,mod)
    n = mod
    s += ch[div]
    dig -= 1
s += ch[mod]
print(s)


import numpy as np
import scipy.sparse as sps
import scipy.misc as spm
import collections as col
import functools as func
import itertools as ite
import fractions as frac
import math as ma
from math import cos,sin,tan,sqrt
import cmath as cma
import copy as cp
import sys
import re
import bisect as bs
sys.setrecursionlimit(10**7)
EPS = sys.float_info.epsilon
PI = np.pi; EXP = np.e; INF = np.inf
MOD = 10**9 + 7

def sinput(): return sys.stdin.readline().strip()
def iinput(): return int(sinput())
def imap(): return map(int, sinput().split())
def fmap(): return map(float, sinput().split())
def iarr(n=0):
    if n: return [0 for _ in range(n)]
    else: return list(imap())
def farr(): return list(fmap())
def sarr(n=0):
    if n: return ["" for _ in range(n)]
    else: return sinput().split()
def barr(n): return [False for _ in range(n)]
def adj(n): return [[] for _ in range(n)]

n = iinput()
ch = ["z"]+[chr(i) for i in range(ord("a"), ord("a")+25)]

ans = ""
while n>0:
    if n%26: ans = ch[n%26] + ans; n //= 26
    else: ans = ch[n%26] + ans; n //= 26; n -= 1
print(ans)


Verdicts: Runtime Error

Accepted