import java.util.*;
public class ExcelColumnTitle {
    public static String numbertocol(int n){
        StringBuilder s=new StringBuilder();
        while(n>0){
            n--;
            int rem=n%26;
            s.append((char) ('A'+rem));
            n/=26;
        }
        return s.reverse().toString();
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        if(!sc.hasNextInt()){
        System.out.println("Invalid input");
               System.exit(0);
        }  else{
               int n= sc.nextInt();
        if(n<1){ 
            System.out.println("Invalid input");
            System.exit(0);
        }
        System.out.println( numberToColumn(n));
        }
    }
}