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 C++ (GCC 9.2.1) (judge verdict: Wrong Answer)

//g++ -std=gnu++14 a.cpp
//#include <bits/stdc++.h>

#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <iostream>
#include <istream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#include <tuple>
#include <iomanip>
#include <random>
#include <math.h>

using namespace std;

#define ll long long
#define rep(i, n) for(ll i = 0; i < (n); i++)
ll MOD = 1e9 + 7;
int INF = 1 << 30;
ll INFL = 1LL << 60;

vector<int> sort(vector<int> &v){
  int l = v.size();
  int i = 0;
  while(i != l-1){
    for(int j = l-1;j > i;j--)if(v[j-1] > v[j])swap(v[j],v[j-1]);
    i++;
  }
  return v;
}

int main(){
   ll N;
   cin >> N;
   string ans = "";

   int keta;
   ll m = 26;

  for(int i = 1; i < 15;i++){
    if(m >= N){
      keta = i;
      break;
    }else{
      ll plus = 1;
      rep(j,i+1)plus *= 26;
      m = m + plus;
    }
  }

  //ll ban = N -

  ll wari = 1;
  rep(i,keta-1)wari *= 26;
  //vector<int> ans;
  while(N > 0){
    int t;
    for(int i = 1;i <= 26;i++){
      if(wari*26 <= N){
        t = 26;
        break;
      }
      if(wari*i > N){
        t = i-1;
        break;
      }else{
        continue;
      }

    }
    //int t = N/(wari);
    //if(t == 27)t--;
    char s = 96 + t;
    ans += s;
    N -= wari*t;
    if(wari != 1)wari /= 26;
  }

  cout << ans << endl;



}