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: Accepted)

#include <iostream>
#include <iomanip>
#include <string>
#include <cmath>
#include <numeric>
#include <climits>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <stack>
#include <queue>
#include <deque>
#include <algorithm>
#include <functional>
#include <utility>
#include <cctype>
#include <iterator>
////////////////////////////////////////////////
#define REP(i, n) for (int i = 0; i < (int)n; i++)
#define FOR(i, m, n) for (int i = (int)m; i < (int)n; i++)
#define REPvec(itr, mp) for (auto itr = mp.begin(); itr != mp.end(); itr++)
#define REPe(e, mp) for (auto& e : mp)
#define all(x) x.begin(), x.end()
#define MOD 1000000007  // 1e9+7
using namespace std;
using ll = long long int;
using vecint = vector<int>;
using vecll = vector<ll>;
using vec2int = vector<vector<int>>;
using P = pair<int, int>;
////////////////////////////////////////////////
////////////////////////////////////////////////
int main() {
  ////////////////////////////////////////////////
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  ////////////////////////////////////////////////
  ll n;
  cin >> n;
  ll m = 0;
  ll x = 0;
  vector<ll> b;
  while (x <= n) {
    x = x + pow(26LL, m);
    b.push_back(x);
    m++;
  }
  // REPe(e, b) cout << e << endl;
  m--;
  n -= b[m - 1];
  // cout << n << endl;
  vecint a(m, 0);
  ll k = 26;
  for (int i = 0; i < m; i++) {
    a[i] = n % k;
    n = n / k;
    // cout << k << " " << a[i] << " " << n << endl;
  }
  // REP(i, m) { cout << a[i] << endl; }
  string s(m, 'a');
  REP(i, m) { s[m - i - 1] = ('a' + a[i]); }
  cout << s << endl;
}