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)

// 問題の URL を書いておく
// 

#include <algorithm>
#include <bitset>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <vector>

using namespace std;

//#define ENABLE_PRINT

#if defined(ENABLE_PRINT)

#define Print(v) \
do {\
    cout << #v << ": " << v << endl; \
}while(0)

#define PrintVec(v) \
do {\
    for(int __i = 0; __i < v.size(); ++__i) \
    { \
        cout << #v << "[" << __i << "]: " << v[__i] << endl; \
    }\
}while(0)

#else

#define Print(v) ((void)0)
#define PrintVec(v) ((void)0)

#endif

#define rep(i, n) for(int i = 0; i < (int)(n); ++i)

const int64_t MAX = 1000000000000001;
const int64_t DIGIT = 26;

int main(int, const char**)
{
    int n;
    cin >> n;
    int base = 0;
    int c = 1;
    int dn = 0;
    while(base < n)
    {
        c *= DIGIT;
        base += c;
        dn++;
    }
    int ob = n - (base - c) - 1;

    Print(dn);
    Print(ob);    

    string ans = "";
    rep(i, dn)
    {
        auto index = ob % DIGIT;
        ans = (char)('a' + index) + ans;
        ob -= index;
        ob /= DIGIT;
    }
    cout << ans << endl;
    return 0;
}