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 <stdio.h>
#include <stdlib.h>
#include <string.h>

const int alCount = 26;
char moji[] = "abcdefghijklmnopqrstuvwxyz"; 
char word;
typedef char String[1024];
String output = "";
int powI(int a, int b)//int型で累乗計算
{   
    if(b == 0){
        return 1;
    }
    int c = 1;
    for (int i = 0; i < b; i++)
    {
        c = c * a;
    }
    return c;
}

int digit(int input) //桁数を計算して返す
{
    int a = 1;
    while (input > powI(alCount,a))
    {
        a++;
    }
    
    return a;
}


void add(int key)//数値入力をして結果を加える
{
    int nKey = key - 1;
    word = moji[nKey];
    strcat(output,&word);
}
void result()//結果を表示S
{
    printf("%s",output);
}
int main(void)
{
    String inString;
    scanf("%s", inString);
    int input = atoi(inString);

    int a = digit(input);
    int counter;
    while (a>0)
    {   
        int odd = powI(alCount,a-1);
        while(input >= odd)
        {
            counter++;
            input = input - odd;
        }
        add(counter);
        a--;
        counter = 0;
    }
    
    result();
    return 0;
}