import java.util.Scanner;

public class Main {	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		
		long N = sc.nextLong();
		long keta = N/25;
		int alp = (int) (N%25);
		
		if(alp == 0){
			for(int i=0; i<keta-1; i++){
				sb.append("A");
			}
			sb.append("Z");
		}else{
			for(int i=0; i<keta; i++){
				sb.append("A");
			}
			if(alp == 1){
				sb.append("A");
			}else if(alp == 2){
				sb.append("B");
			}else if(alp == 3){
				sb.append("C");
			}else if(alp == 4){
				sb.append("D");
			}else if(alp == 5){
				sb.append("E");
			}else if(alp == 6){
				sb.append("F");
			}else if(alp == 7){
				sb.append("G");
			}else if(alp == 8){
				sb.append("H");
			}else if(alp == 9){
				sb.append("I");
			}else if(alp == 10){
				sb.append("J");
			}else if(alp == 11){
				sb.append("K");
			}else if(alp == 12){
				sb.append("L");
			}else if(alp == 13){
				sb.append("M");
			}else if(alp == 14){
				sb.append("N");
			}else if(alp == 15){
				sb.append("O");
			}else if(alp == 16){
				sb.append("P");
			}else if(alp == 17){
				sb.append("Q");
			}else if(alp == 18){
				sb.append("R");
			}else if(alp == 19){
				sb.append("S");
			}else if(alp == 20){
				sb.append("T");
			}else if(alp == 21){
				sb.append("U");
			}else if(alp == 22){
				sb.append("V");
			}else if(alp == 23){
				sb.append("W");
			}else if(alp == 24){
				sb.append("X");
			}else if(alp == 25){
				sb.append("Y");
			}else if(alp == 26){
				sb.append("Z");
			}
		}
		String ans = sb.toString();
		System.out.println(ans);
	}
}