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 Java (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.FileNotFoundException;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws FileNotFoundException {

//    	File file = new File("src/in.txt");

        //コード
//    	Scanner sc = new Scanner(file);
    	Scanner sc = new Scanner(System.in);

    	long N = sc.nextLong();
    	if(N==1) {
    		System.out.println("a");
    	} else {

    		long X = 26;
    		int cnt = 0;
    		while(X<N) {
    			X = 26 * (X+1);
    			cnt++;
    		}
    		X = X/26 -1 ;
        	N = N-X-1;
        	long[] x = new long[11];
        	int keta = 0;
        	while(N>0) {
        		x[keta] = N%26;
        		keta++;
        		N = N/26;
        	}
        	for(int i=cnt;i>=0;i--) {
        		if(i>0) {
        			long y = x[i];
        			long codepoint =  97+y;
        			char c = (char)codepoint;
        			System.out.print(c);
        		} else {
        			long y = x[i];
        			y++;
        			long codepoint =  96+y;
        			char c = (char)codepoint;
        			System.out.println(c);
        		}
        	}
    	}
    }
}