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>

void revStr(char *str){
  int size = strlen(str);
  char tmp = {0};

  for(int i=0,j=size-1;i<size/2;i++,j--){
    tmp = str[i];
    str[i]=str[j];
    str[j] = tmp;
  }
}

char ans[1000]="";
//convert x to n
void convert(long long int x,long long int n){
  long long int i=0;
  while(1){
    if(x == 0) break;
    if(x%n == 0){
      ans[i]= 'a' + (n-1);
      x = x/n -1;
    }else{
      ans[i]='a' + (x%n-1);
      x /= n;
    }
    i++;
  }
}

int main(){
  //long long int max=1000000000000001;
  long long int N = 1;
  scanf("%I64d",&N);
  convert(N,26);
  revStr(ans);
  printf("%s\n",ans);
  return 0;
}