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)

from collections import Counter
from collections import defaultdict
from collections import deque
from functools import reduce
import math
import itertools
import heapq
#import numpy as np
import bisect
import sys
#import sympy
sys.setrecursionlimit(10**6)


def bfs(s, n, node):
    # 頂点が探索済みかどうかのチェック配列
    check = [False for _ in range(n)]
    check[s] = True
    # 次見る頂点を格納するキュー
    queue = deque([s])
    visited_num = 1

    # 問題固有の配列
    #color_check=[[True for _ in range(l)] for _ in range(n)]
    color = [-1 for _ in range(n)]
    color[s] = 0

    while visited_num < n:
        # グラフが全連結ではない場合
        if len(queue) == 0:
            # 空配列を返す
            # 現状までの計算済み配列を返してもいいと思う
            return color

        now_vertex = queue.popleft()
        # インデックスがない場合は
        for next_vertex in node[now_vertex]:

            if check[next_vertex] == True:
                continue

            queue.append(next_vertex)
            check[next_vertex] = True

            # 問題固有の計算
            color[next_vertex] = color[now_vertex]+1
            visited_num += 1

    return color


mod = 10**9+7
# n=int(input())
# n,m=list(map(int,input().split()))
# a=list(map(int,input().split()))
def ceil(x, y): return (x+y-1)//y
def input_list(): return list(map(int, input().split()))


n = int(input())
n -= 1
num = 26
ans = []
while n >= num:
    k = n % num
    ans.append(k)
    n //= num
    n -= 1
ans.append(n)
# print(ans)
ans = (list(map(lambda x: chr(x+ord("a")), ans)))
print("".join(ans)[::-1])