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 <math.h>

int main(void)
{
    long long int N, N_copy, N_long, tmp;
    int ans;
    int i, l=1;//Nは何文字か
    scanf("%lld",&N);
    N_copy = N;
    
    N_long = 0;
    while(N > N_long){
        N_long += pow(26,l);
        l++;
        //printf("Nlong = %lld\n",N_long);
    }
    l--;
    //printf("l = %d\n",l);
    l--;
    N_copy = N;
    for(i=l; i>0; i--){
        tmp = pow(26,i);
        //printf("tmp = %lld\n",tmp);
        ans = N_copy/tmp;
        N_copy = N_copy%tmp;
        printf("%c",ans+96);
    }
    //printf("N_copy = %lld\n",N_copy);
    printf("%c\n",(char)N_copy +96);
    
    return 0;
}