import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		long n = s.nextLong();
		
		int ctr = 0;
		long num = 0;
		
		while(n>num*26+26) {
			num = num*26+26;
			ctr++;
		}
		n = n-num-1;
		while(ctr>=0) {
			long ans = (long)(Math.pow(26, ctr));
			long r = (n/ans);
			System.out.print((char)(r+97));
			n = n%ans;
			ctr--;
		}
		
		
	}

} import java.util.Scanner; Scanner java.util public class Main {
	
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		long n = s.nextLong();
		
		int ctr = 0;
		long num = 0;
		
		while(n>num*26+26) {
			num = num*26+26;
			ctr++;
		}
		n = n-num-1;
		while(ctr>=0) {
			long ans = (long)(Math.pow(26, ctr));
			long r = (n/ans);
			System.out.print((char)(r+97));
			n = n%ans;
			ctr--;
		}
		
		
	}

} Main public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		long n = s.nextLong();
		
		int ctr = 0;
		long num = 0;
		
		while(n>num*26+26) {
			num = num*26+26;
			ctr++;
		}
		n = n-num-1;
		while(ctr>=0) {
			long ans = (long)(Math.pow(26, ctr));
			long r = (n/ans);
			System.out.print((char)(r+97));
			n = n%ans;
			ctr--;
		}
		
		
	} main {
		Scanner s = new Scanner(System.in);
		long n = s.nextLong();
		
		int ctr = 0;
		long num = 0;
		
		while(n>num*26+26) {
			num = num*26+26;
			ctr++;
		}
		n = n-num-1;
		while(ctr>=0) {
			long ans = (long)(Math.pow(26, ctr));
			long r = (n/ans);
			System.out.print((char)(r+97));
			n = n%ans;
			ctr--;
		}
		
		
	} Scanner s = new Scanner(System.in); s new Scanner(System.in) long n = s.nextLong(); n s.nextLong() s.nextLong s int ctr = 0; ctr 0 long num = 0; num 0 while(n>num*26+26) {
			num = num*26+26;
			ctr++;
		} n>num*26+26 n num*26+26 num*26 num 26 26 {
			num = num*26+26;
			ctr++;
		} num = num*26+26 num num*26+26 num*26 num 26 26 ctr++ ctr n = n-num-1 n n-num-1 n-num-1 n num 1 while(ctr>=0) {
			long ans = (long)(Math.pow(26, ctr));
			long r = (n/ans);
			System.out.print((char)(r+97));
			n = n%ans;
			ctr--;
		} ctr>=0 ctr 0 {
			long ans = (long)(Math.pow(26, ctr));
			long r = (n/ans);
			System.out.print((char)(r+97));
			n = n%ans;
			ctr--;
		} long ans = (long)(Math.pow(26, ctr)); ans (long)(Math.pow(26, ctr)) Math.pow Math 26 ctr long r = (n/ans); r (n/ans) n ans System.out.print((char)(r+97)) System.out.print System.out System System.out (char)(r+97) r 97 n = n%ans n n%ans n ans ctr-- ctr String[] args args public class Main {
	
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		long n = s.nextLong();
		
		int ctr = 0;
		long num = 0;
		
		while(n>num*26+26) {
			num = num*26+26;
			ctr++;
		}
		n = n-num-1;
		while(ctr>=0) {
			long ans = (long)(Math.pow(26, ctr));
			long r = (n/ans);
			System.out.print((char)(r+97));
			n = n%ans;
			ctr--;
		}
		
		
	}

} public class Main {
	
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		long n = s.nextLong();
		
		int ctr = 0;
		long num = 0;
		
		while(n>num*26+26) {
			num = num*26+26;
			ctr++;
		}
		n = n-num-1;
		while(ctr>=0) {
			long ans = (long)(Math.pow(26, ctr));
			long r = (n/ans);
			System.out.print((char)(r+97));
			n = n%ans;
			ctr--;
		}
		
		
	}

} Main
import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		long n = s.nextLong();
		
		int ctr = 0;
		long num = 0;
		
		while(n>num*26+26) {
			num = num*26+26;
			ctr++;
		}
		n = n-num-1;
		while(ctr>=0) {
			long ans = (long)(Math.pow(26, ctr));
			long r = (n/ans);
			System.out.print((char)(r+97));
			n = n%ans;
			ctr--;
		}
		
		
	}

}
