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<stdio.h>

int main(){
  unsigned long long a[30];
  unsigned long long b[30];
  char n[30];
  int cnt,i;
  unsigned long long A;
	
  	scanf("%llu",&A);
	
    b[0] = (unsigned long long)A%26;
    a[0] = ((unsigned long long)A/26);
     if(b[0] == 0){
       a[0] = a[0]-1;
     }

 	for(i=0;i<20;i++){
	      if(a[i] == 0){
	        cnt = i;
	        break;
	      }
 		
	  	b[i+1] = a[i]%26;
 		a[i+1] = (a[i]/26);
	     if(b[i+1] == 0){
   	     a[i+1] = a[i+1]-1;
   		 }
    }
	
  	for(i=cnt;i>=0;i--){
      	if(b[i] != 0){
    		n[i] = b[i]+96;
        }else{
         	n[i] = 122;
        }
    }
	
  	for(i=cnt;i>=0;i--){
     	printf("%c",n[i]); 
    }
  
}