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(){
  long long n;
  scanf("%lld",&n);
  int a[12];
  
  long long b[12];
  
  b[0]=1;
  
  int k;
  
  for(int i=1;i<=11;i++){
    b[i]=b[i-1]*26;
  }
  
  long long m=n;
  
  for(int i=1;i<=11;i++){
    m-=b[i];
    if(m<=0){k=i;break;}
  }
  
  n=m+b[k]-1;
  
  
  for(int i=k-1;i>=0;i--){
    a[i]=(n-n%b[i])/b[i];
    n=n%b[i];
  }
  
  for(int i=k-1;i>=0;i--){
    if(a[i]==0){printf("a");}
    if(a[i]==1){printf("b");}
    if(a[i]==2){printf("c");}
    if(a[i]==3){printf("d");}
    if(a[i]==4){printf("e");}
    if(a[i]==5){printf("f");}
    if(a[i]==6){printf("g");}
    if(a[i]==7){printf("h");}
    if(a[i]==8){printf("i");}
    if(a[i]==9){printf("j");}
    if(a[i]==10){printf("k");}
    if(a[i]==11){printf("l");}
    if(a[i]==12){printf("m");}
    if(a[i]==13){printf("n");}
    if(a[i]==14){printf("o");}
    if(a[i]==15){printf("p");}
    if(a[i]==16){printf("q");}
    if(a[i]==17){printf("r");}
    if(a[i]==18){printf("s");}
    if(a[i]==19){printf("t");}
    if(a[i]==20){printf("u");}
    if(a[i]==21){printf("v");}
    if(a[i]==22){printf("w");}
    if(a[i]==23){printf("x");}
    if(a[i]==24){printf("y");}
    if(a[i]==25){printf("z");}
  }
  
  return 0;
}