import java.util.Scanner;

public class Main{

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn=new Scanner(System.in);
		long n=scn.nextLong();
	        System.out.println( res(n));

	}
	public static StringBuilder res(long n){
		if(n<=0){
			StringBuilder sb=new StringBuilder();
			return sb;
		}
		if(n<=26){
			StringBuilder sb=new StringBuilder();
			char ch = (char)((n-1)+'a');
			sb.append(ch);
			return sb;
		}
		  StringBuilder ans=new StringBuilder();
		  if(n%26==0){
		StringBuilder a= res(n/26-1);
		  ans.append(a);
		  }else{
			  StringBuilder a= res(n/26);
			  ans.append(a);
		  }
		  
		    long val=n%26;
		    if(val==0){
		    	val=26;
		    }
		    char ch=(char)((val-1)+'a');
		    ans.append(ch);
		    return ans;
		
	}

}
/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