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

/*
	入力例：
	3
	1 1 3
*/

int main(){
	int i,j;
	long strInput[1];
	for(int i=0;i<1;i++){
	 scanf("%ld", &strInput[i]);
	}

	char strRet[20];
	memset(strRet,0x00,20);
	long tmp=0;
	tmp=strInput[0];
	for(i=0;tmp>0;i++){
			strRet[18-i]='a'+((tmp-1)%26);
//		printf("%d--%c\n",tmp,strRet[15-i]);

		tmp= (long)((tmp - ((tmp-1)%26))/26);
	}
//	printf("end -- %d\n",lastIdx);
	
//	printf("%s\n",strRet[15 - lastIdx +1]);
	char* strRet2;
	for (i=0;i<19;i++){
		if (strRet[i]!=0x00){
			strRet2 = &strRet[i];
			break;
		}
	}
	printf("%s\n",strRet2);
  return 0;
}