import java.util.*; public class No327{ public static void main(String[] args){ Scanner sc = new Scanner(System.in); long n = sc.nextLong(); if(n < 26){ System.out.println((char)(65+n)); return; } StringBuilder sb = new StringBuilder(); int pow = 9; while((long)Math.pow(26, pow) > n){ pow--; } for(int p = pow; p >= 0; p--){ long div = (long)Math.pow(26, p); if(p == pow){ sb.append((char)(64+n/div)); }else{ sb.append((char)(65+n/div)); } n %= div; } System.out.println(sb); } }