import java.util.*;
 
public class Main {
    public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String str = "";
      	System.out.println(new StringBuilder(detectChar(a, str)).reverse().toString());
    }

	public static String detectChar(long a, String b) {
        a--;  
      	String c = b + returnChar(a%26);
      	a /= 26;
        if (a > 0) {
          return detectChar(a, c);
        } else {
          return c;
        }
	}

	public static char returnChar(long a) {
      	return (char)('a' + a % 26);
	}
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String str = "";
      	System.out.println(new StringBuilder(detectChar(a, str)).reverse().toString());
    }

	public static String detectChar(long a, String b) {
        a--;  
      	String c = b + returnChar(a%26);
      	a /= 26;
        if (a > 0) {
          return detectChar(a, c);
        } else {
          return c;
        }
	}

	public static char returnChar(long a) {
      	return (char)('a' + a % 26);
	}
} Main public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String str = "";
      	System.out.println(new StringBuilder(detectChar(a, str)).reverse().toString());
    } main {
		Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String str = "";
      	System.out.println(new StringBuilder(detectChar(a, str)).reverse().toString());
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long a = sc.nextLong(); a sc.nextLong() sc.nextLong sc String str = ""; str "" System.out.println(new StringBuilder(detectChar(a, str)).reverse().toString()) System.out.println System.out System System.out new StringBuilder(detectChar(a, str)).reverse().toString() new StringBuilder(detectChar(a, str)).reverse().toString new StringBuilder(detectChar(a, str)).reverse() new StringBuilder(detectChar(a, str)).reverse new StringBuilder(detectChar(a, str)) String[] args args public static String detectChar(long a, String b) {
        a--;  
      	String c = b + returnChar(a%26);
      	a /= 26;
        if (a > 0) {
          return detectChar(a, c);
        } else {
          return c;
        }
	} detectChar {
        a--;  
      	String c = b + returnChar(a%26);
      	a /= 26;
        if (a > 0) {
          return detectChar(a, c);
        } else {
          return c;
        }
	} a-- a String c = b + returnChar(a%26); c b + returnChar(a%26) b returnChar(a%26) returnChar a%26 a 26 a /= 26 a 26 if (a > 0) {
          return detectChar(a, c);
        } else {
          return c;
        } a > 0 a 0 {
          return detectChar(a, c);
        } return detectChar(a, c); detectChar(a, c) detectChar a c {
          return c;
        } return c; c long a a String b b public static char returnChar(long a) {
      	return (char)('a' + a % 26);
	} returnChar {
      	return (char)('a' + a % 26);
	} return (char)('a' + a % 26); (char)('a' + a % 26) 'a' a % 26 a 26 long a a public class Main {
    public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String str = "";
      	System.out.println(new StringBuilder(detectChar(a, str)).reverse().toString());
    }

	public static String detectChar(long a, String b) {
        a--;  
      	String c = b + returnChar(a%26);
      	a /= 26;
        if (a > 0) {
          return detectChar(a, c);
        } else {
          return c;
        }
	}

	public static char returnChar(long a) {
      	return (char)('a' + a % 26);
	}
} public class Main {
    public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String str = "";
      	System.out.println(new StringBuilder(detectChar(a, str)).reverse().toString());
    }

	public static String detectChar(long a, String b) {
        a--;  
      	String c = b + returnChar(a%26);
      	a /= 26;
        if (a > 0) {
          return detectChar(a, c);
        } else {
          return c;
        }
	}

	public static char returnChar(long a) {
      	return (char)('a' + a % 26);
	}
} Main
import java.util.*;
 
public class Main {
    public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
        long a = sc.nextLong();
        String str = "";
      	System.out.println(new StringBuilder(detectChar(a, str)).reverse().toString());
    }

	public static String detectChar(long a, String b) {
        a--;  
      	String c = b + returnChar(a%26);
      	a /= 26;
        if (a > 0) {
          return detectChar(a, c);
        } else {
          return c;
        }
	}

	public static char returnChar(long a) {
      	return (char)('a' + a % 26);
	}
}