import java.util.Scanner;

public class Main {
    
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        final long N = sc.nextLong() - 1;
        final int NUM = 26;
        
        StringBuilder str = new StringBuilder();
        str.append((char) ('a' + N % NUM));
        long n = N / NUM;
        
        while (0 < n) {
            str.append((char) ('a' + (n - 1) % NUM));
            n = (n - 1) / NUM;
        }
        
        System.out.println(str.reverse());
    }
} import java.util.Scanner; Scanner java.util public class Main {
    
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        final long N = sc.nextLong() - 1;
        final int NUM = 26;
        
        StringBuilder str = new StringBuilder();
        str.append((char) ('a' + N % NUM));
        long n = N / NUM;
        
        while (0 < n) {
            str.append((char) ('a' + (n - 1) % NUM));
            n = (n - 1) / NUM;
        }
        
        System.out.println(str.reverse());
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        final long N = sc.nextLong() - 1;
        final int NUM = 26;
        
        StringBuilder str = new StringBuilder();
        str.append((char) ('a' + N % NUM));
        long n = N / NUM;
        
        while (0 < n) {
            str.append((char) ('a' + (n - 1) % NUM));
            n = (n - 1) / NUM;
        }
        
        System.out.println(str.reverse());
    } main {
        Scanner sc = new Scanner(System.in);
        
        final long N = sc.nextLong() - 1;
        final int NUM = 26;
        
        StringBuilder str = new StringBuilder();
        str.append((char) ('a' + N % NUM));
        long n = N / NUM;
        
        while (0 < n) {
            str.append((char) ('a' + (n - 1) % NUM));
            n = (n - 1) / NUM;
        }
        
        System.out.println(str.reverse());
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) final long N = sc.nextLong() - 1; N sc.nextLong() - 1 sc.nextLong() sc.nextLong sc 1 final int NUM = 26; NUM 26 StringBuilder str = new StringBuilder(); str new StringBuilder() str.append((char) ('a' + N % NUM)) str.append str (char) ('a' + N % NUM) 'a' N % NUM N NUM long n = N / NUM; n N / NUM N NUM while (0 < n) {
            str.append((char) ('a' + (n - 1) % NUM));
            n = (n - 1) / NUM;
        } 0 < n 0 n {
            str.append((char) ('a' + (n - 1) % NUM));
            n = (n - 1) / NUM;
        } str.append((char) ('a' + (n - 1) % NUM)) str.append str (char) ('a' + (n - 1) % NUM) 'a' (n - 1) % NUM (n - 1) n 1 NUM n = (n - 1) / NUM n (n - 1) / NUM (n - 1) n 1 NUM System.out.println(str.reverse()) System.out.println System.out System System.out str.reverse() str.reverse str String[] args args public class Main {
    
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        final long N = sc.nextLong() - 1;
        final int NUM = 26;
        
        StringBuilder str = new StringBuilder();
        str.append((char) ('a' + N % NUM));
        long n = N / NUM;
        
        while (0 < n) {
            str.append((char) ('a' + (n - 1) % NUM));
            n = (n - 1) / NUM;
        }
        
        System.out.println(str.reverse());
    }
} public class Main {
    
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        final long N = sc.nextLong() - 1;
        final int NUM = 26;
        
        StringBuilder str = new StringBuilder();
        str.append((char) ('a' + N % NUM));
        long n = N / NUM;
        
        while (0 < n) {
            str.append((char) ('a' + (n - 1) % NUM));
            n = (n - 1) / NUM;
        }
        
        System.out.println(str.reverse());
    }
} Main
import java.util.Scanner;

public class Main {
    
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        final long N = sc.nextLong() - 1;
        final int NUM = 26;
        
        StringBuilder str = new StringBuilder();
        str.append((char) ('a' + N % NUM));
        long n = N / NUM;
        
        while (0 < n) {
            str.append((char) ('a' + (n - 1) % NUM));
            n = (n - 1) / NUM;
        }
        
        System.out.println(str.reverse());
    }
}
