import java.util.*;

public class Main {



    public static void main(String[] args) {

        //1_000_000_000_000_001    15


        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();


        StringBuilder sb = new StringBuilder();

        boolean exit = false;
        while(!exit){
            int m = (int)((N-1)%26L);
            char c = (char)('a'+ m);
            sb.insert(0,c);
            N = (N-1)/26L;
            if(N ==0L) exit=true;
        }
        System.out.println(sb.toString());


    }

} import java.util.*; util.* java public class Main {



    public static void main(String[] args) {

        //1_000_000_000_000_001    15


        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();


        StringBuilder sb = new StringBuilder();

        boolean exit = false;
        while(!exit){
            int m = (int)((N-1)%26L);
            char c = (char)('a'+ m);
            sb.insert(0,c);
            N = (N-1)/26L;
            if(N ==0L) exit=true;
        }
        System.out.println(sb.toString());


    }

} Main public static void main(String[] args) {

        //1_000_000_000_000_001    15


        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();


        StringBuilder sb = new StringBuilder();

        boolean exit = false;
        while(!exit){
            int m = (int)((N-1)%26L);
            char c = (char)('a'+ m);
            sb.insert(0,c);
            N = (N-1)/26L;
            if(N ==0L) exit=true;
        }
        System.out.println(sb.toString());


    } main {

        //1_000_000_000_000_001    15


        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();


        StringBuilder sb = new StringBuilder();

        boolean exit = false;
        while(!exit){
            int m = (int)((N-1)%26L);
            char c = (char)('a'+ m);
            sb.insert(0,c);
            N = (N-1)/26L;
            if(N ==0L) exit=true;
        }
        System.out.println(sb.toString());


    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long N = sc.nextLong(); N sc.nextLong() sc.nextLong sc StringBuilder sb = new StringBuilder(); sb new StringBuilder() boolean exit = false; exit false while(!exit){
            int m = (int)((N-1)%26L);
            char c = (char)('a'+ m);
            sb.insert(0,c);
            N = (N-1)/26L;
            if(N ==0L) exit=true;
        } !exit exit {
            int m = (int)((N-1)%26L);
            char c = (char)('a'+ m);
            sb.insert(0,c);
            N = (N-1)/26L;
            if(N ==0L) exit=true;
        } int m = (int)((N-1)%26L); m (int)((N-1)%26L) (N-1) N 1 26L char c = (char)('a'+ m); c (char)('a'+ m) 'a' m sb.insert(0,c) sb.insert sb 0 c N = (N-1)/26L N (N-1)/26L (N-1) N 1 26L if(N ==0L) exit=true; N ==0L N 0L exit=true exit true System.out.println(sb.toString()) System.out.println System.out System System.out sb.toString() sb.toString sb String[] args args public class Main {



    public static void main(String[] args) {

        //1_000_000_000_000_001    15


        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();


        StringBuilder sb = new StringBuilder();

        boolean exit = false;
        while(!exit){
            int m = (int)((N-1)%26L);
            char c = (char)('a'+ m);
            sb.insert(0,c);
            N = (N-1)/26L;
            if(N ==0L) exit=true;
        }
        System.out.println(sb.toString());


    }

} public class Main {



    public static void main(String[] args) {

        //1_000_000_000_000_001    15


        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();


        StringBuilder sb = new StringBuilder();

        boolean exit = false;
        while(!exit){
            int m = (int)((N-1)%26L);
            char c = (char)('a'+ m);
            sb.insert(0,c);
            N = (N-1)/26L;
            if(N ==0L) exit=true;
        }
        System.out.println(sb.toString());


    }

} Main
import java.util.*;

public class Main {



    public static void main(String[] args) {

        //1_000_000_000_000_001    15


        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();


        StringBuilder sb = new StringBuilder();

        boolean exit = false;
        while(!exit){
            int m = (int)((N-1)%26L);
            char c = (char)('a'+ m);
            sb.insert(0,c);
            N = (N-1)/26L;
            if(N ==0L) exit=true;
        }
        System.out.println(sb.toString());


    }

}
