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)

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
typedef pair<ll, ll> Pll;
using Graph = vector<vector<int>>;
using Graphl = vector<vector<ll>>;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define Rep(i, k, n) for (int i = k; i < (int)(n); i++)
#define RRep(i, k, n) for (int i = k; i > (int)(n); i--)
#define FOR(itr, v) for (auto itr = (v).begin(); itr != (v).end(); ++itr)
#define COUT(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << endl
#define ALL(a)  (a).begin(),(a).end()
#define rALL(a)  (a).rbegin(),(a).rend()
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<class T> void PrintVector(const vector<T> &vec) {for (auto val : vec) cout << val << " "; cout << endl;}
const long long INF = 1LL << 60;
const long long minusINF = -(1LL << 40);
const int MOD = 1000000007;
const double PI = acos(-1); //3.14~
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
char num[26] = {'z', 'a', 'b','c'};

// 多倍長テンプレ
/* ---------------------- ここから ---------------------- */
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <boost/multiprecision/cpp_int.hpp>
namespace mp = boost::multiprecision;
// 任意長整数型
using Bint = mp::cpp_int;
// 仮数部が1024ビットの浮動小数点数型(TLEしたら小さくする)
using Real = mp::number<mp::cpp_dec_float<1024>>;
/* ---------------------- ここまで ---------------------- */

int main()
{
    Bint n; cin >> n;
    string ans = "";
    if (n > 0 && n < 27)
    {
        char c = (int)n + 96;
        cout << c << endl;
        return 0;
    }
    while(1)
    {
        if (n % 26 == 0) ans += 'z';
        else ans += (char)((n % 26) + 96);

        if (n / 26 == 0) break;
        n /= 26;
    }
    reverse(ALL(ans));
    cout << ans << endl;
}