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 <bits/stdc++.h>
#include <iostream>
#include <queue>
#include <stack>
#include <vector>
#include <string>
#include <set>
#include <map>
#include <random>
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define repp(i,n,m) for (int i = m; i < (n); ++i)
#define repl(i,n) for (long long i = 0; i < (n); ++i)
#define reppl(i,n,m) for (long long i = m; i < (n); ++i)
using namespace std;
using ll = long long;
using ld = long double;
using P = pair<int, int>;
using PL = pair<long long, long long>;
using Pxy = pair<double, double>;
using T = tuple<int, int, bool>;
const int INF = 1001001007;
const int mod = 1000000007;
const int MOD = 998244353;
const ll inf = 1e18;
template <typename AT>
void printvec(vector<AT> &ar){
    rep(i,ar.size()-1) cout << ar[i] << " ";
    cout << ar[ar.size()-1] << endl;
}
template <typename Q>
void printvvec(vector<vector<Q>> &ar){
    rep(i,ar.size()){
        rep(j,ar[0].size()-1) cout << ar[i][j] << " ";
        cout << ar[i][ar[0].size()-1] << endl;
    }
}
template <typename S>
bool range(S a, S b, S x){
    return (a <= x && x < b);
}

int main() {
    ll n; cin >> n;
    string s = "";
    vector<int> ar;
    while (true){
        int a = n % 26;
        n -= a;
        if (a == 0){
            n -= 26;
            s += 'z';
        }
        else {
            char c = 'a';
            rep(i,a-1) c++;
            s += c;
        }
        n /= 26;
        if (n == 0) break;
    }
    string ans = "";
    int m = s.size();
    rep(i,m) ans += s[m-1-i];
    cout << ans << endl;
}