
import java.util.*;

public class Main {
	static public void main(String args[]){
		Scanner sc=new Scanner(System.in);
		
		Long nu=sc.nextLong();
		
		String str="abcdefghijklmnopqrstuvwxyz";
		List<String>list=new ArrayList<>();
		
		do{
			nu--;
			String s=Long.toString(nu%26);
			//System.out.print(s);
			list.add(s);
			nu/=26;
		}while(nu>0);
		
	
		for(int i=list.size()-1;i>=0;i--){
			int a=Integer.parseInt(list.get(i));
			//System.out.print(a);
			System.out.print(str.charAt(a));
		}
	}
}
/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