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 <string.h>

char *inttoaa(char *s, int n)
{
char *p = s, *q = s;

while(n > 0){
const char *const aa = "zabcdefghijklmnopqrstuvwxy";
int r = n % 26;

n = n / 26 - !r;
*p ++ = aa[r];
}
*p = '\0';
while(p > q){
char c = * -- p;

*p = *q;
*q ++ = c;
}
return s;
}

int aatoint(char *s)
{
int n = 0;

while(*s){
const char *const aa = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const char *p = strchr(aa, *s ++);

if(!p) return 0;
n = n * 26 + (p - aa + 1);
}
return n;
}

int main(void)
{
char s[32];
int i;

scanf("%d", &i);
inttoaa(s, i);
printf("%s \n", s);
return 0;
}