import java.util.*;
public class Main {
    public static long mod(long i, long j) {
    return (i % j) < 0 ? (i % j) + 0 + (j < 0 ? -j : j) : (i % j + 0);
    } 
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
        a--;
		StringBuilder sb = new StringBuilder();
        String str[] = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
        while(a>=0){int b = (int)mod(a,26);                   
                    sb.append(str[b]);
                    a/=26;
                    a--;}
		String ans = sb.toString();
        StringBuffer ans1 = new StringBuffer(ans);
		System.out.println(ans1.reverse().toString());
	}
} import java.util.*; util.* java public class Main {
    public static long mod(long i, long j) {
    return (i % j) < 0 ? (i % j) + 0 + (j < 0 ? -j : j) : (i % j + 0);
    } 
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
        a--;
		StringBuilder sb = new StringBuilder();
        String str[] = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
        while(a>=0){int b = (int)mod(a,26);                   
                    sb.append(str[b]);
                    a/=26;
                    a--;}
		String ans = sb.toString();
        StringBuffer ans1 = new StringBuffer(ans);
		System.out.println(ans1.reverse().toString());
	}
} Main public static long mod(long i, long j) {
    return (i % j) < 0 ? (i % j) + 0 + (j < 0 ? -j : j) : (i % j + 0);
    } mod {
    return (i % j) < 0 ? (i % j) + 0 + (j < 0 ? -j : j) : (i % j + 0);
    } return (i % j) < 0 ? (i % j) + 0 + (j < 0 ? -j : j) : (i % j + 0); (i % j) < 0 ? (i % j) + 0 + (j < 0 ? -j : j) : (i % j + 0) (i % j) < 0 (i % j) i j 0 (i % j) + 0 + (j < 0 ? -j : j) (i % j) + 0 + (j < 0 ? -j : j) (i % j) i j 0 (j < 0 ? -j : j) j < 0 j 0 -j j j (i % j + 0) i % j i j 0 long i i long j j public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
        a--;
		StringBuilder sb = new StringBuilder();
        String str[] = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
        while(a>=0){int b = (int)mod(a,26);                   
                    sb.append(str[b]);
                    a/=26;
                    a--;}
		String ans = sb.toString();
        StringBuffer ans1 = new StringBuffer(ans);
		System.out.println(ans1.reverse().toString());
	} main {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
        a--;
		StringBuilder sb = new StringBuilder();
        String str[] = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
        while(a>=0){int b = (int)mod(a,26);                   
                    sb.append(str[b]);
                    a/=26;
                    a--;}
		String ans = sb.toString();
        StringBuffer ans1 = new StringBuffer(ans);
		System.out.println(ans1.reverse().toString());
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc a-- a StringBuilder sb = new StringBuilder(); sb new StringBuilder() String str[] = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"}; str {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"} "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z" while(a>=0){int b = (int)mod(a,26);                   
                    sb.append(str[b]);
                    a/=26;
                    a--;} a>=0 a 0 {int b = (int)mod(a,26);                   
                    sb.append(str[b]);
                    a/=26;
                    a--;} int b = (int)mod(a,26); b (int)mod(a,26) mod a 26 sb.append(str[b]) sb.append sb str[b] str b a/=26 a 26 a-- a String ans = sb.toString(); ans sb.toString() sb.toString sb StringBuffer ans1 = new StringBuffer(ans); ans1 new StringBuffer(ans) System.out.println(ans1.reverse().toString()) System.out.println System.out System System.out ans1.reverse().toString() ans1.reverse().toString ans1.reverse() ans1.reverse ans1 String[] args args public class Main {
    public static long mod(long i, long j) {
    return (i % j) < 0 ? (i % j) + 0 + (j < 0 ? -j : j) : (i % j + 0);
    } 
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
        a--;
		StringBuilder sb = new StringBuilder();
        String str[] = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
        while(a>=0){int b = (int)mod(a,26);                   
                    sb.append(str[b]);
                    a/=26;
                    a--;}
		String ans = sb.toString();
        StringBuffer ans1 = new StringBuffer(ans);
		System.out.println(ans1.reverse().toString());
	}
} public class Main {
    public static long mod(long i, long j) {
    return (i % j) < 0 ? (i % j) + 0 + (j < 0 ? -j : j) : (i % j + 0);
    } 
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
        a--;
		StringBuilder sb = new StringBuilder();
        String str[] = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
        while(a>=0){int b = (int)mod(a,26);                   
                    sb.append(str[b]);
                    a/=26;
                    a--;}
		String ans = sb.toString();
        StringBuffer ans1 = new StringBuffer(ans);
		System.out.println(ans1.reverse().toString());
	}
} Main
import java.util.*;
public class Main {
    public static long mod(long i, long j) {
    return (i % j) < 0 ? (i % j) + 0 + (j < 0 ? -j : j) : (i % j + 0);
    } 
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
        a--;
		StringBuilder sb = new StringBuilder();
        String str[] = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
        while(a>=0){int b = (int)mod(a,26);                   
                    sb.append(str[b]);
                    a/=26;
                    a--;}
		String ans = sb.toString();
        StringBuffer ans1 = new StringBuffer(ans);
		System.out.println(ans1.reverse().toString());
	}
}