import java.util.*;

class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        long n=scan.nextLong();
        String[] d=new String[32];
        int p=1;
        for(int i=0;i<20;++i){
            d[i]=Character.toString((char)(97+i));
        }
        for(int i=20;i<32;++i){
            int x=(i-20)/4;
            int y=(i-20)%4;
            char[] k={(char)(97+20+x),(char)(97+24+y)};
            d[i]=new String(k);
        }
        String c="a";
        StringBuilder sb=new StringBuilder();
        StringBuilder rev=new StringBuilder();
        int h=-1;
        for(int i=30;i>=0;--i){
            if(1L<<i>n){continue;}
            h=i;break;
        }
        for(int i=h-1;i>=0;--i){
            //2bai
            sb.append(c);
            rev.append(new StringBuilder(c).reverse());
            //+1
            if((n&1<<i)!=0){
                c=d[p++];
                sb.append(c);
                rev.append(new StringBuilder(c).reverse());
            }
        }
        String r=rev.reverse().toString()+sb;
        if(r.length()==0)r="s";
        System.out.println(r);
    }
}