import java.util.*;
class Main{
  public static void main(String args[]){
    Scanner obj=new Scanner(System.in);
    long n=obj.nextLong();
    StringBuilder result = new StringBuilder();

        while(n>0){
            n--;
            result.insert(0, (char)('a' + n % 26));
            n /= 26;
        }

        System.out.println(result.toString());
  }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz