import java.util.*;

public class zigzagnametag_font
{
   public static void main(String[] args)
   {
      new zigzagnametag_font(new Scanner(System.in));
   }

   // Counts the maximum sum you can form using N characters where the
   // last character was in the range [0, 25]. (Works for N >= 0)
   int maxSum(int N, int lastCharacter)
   {
      if (N == 0) return 0;
      int firstSum = Math.max(25-lastCharacter, lastCharacter);
      firstSum += 25*(N-1);
      return firstSum;
   }

   public zigzagnametag_font(Scanner in)
   {
      int K = in.nextInt();
      int N = (K+24)/25+1;

      // Find the first character that allows K to be reachable.
      StringBuilder sb = new StringBuilder();
      int lastCharacter = -1;
      for (int k=0; k<26; k++)
      {
         int sum = maxSum(N-1, k);
         if (sum >= K)
         {
            sb.append((char)('a'+k));
            lastCharacter = k;
            break;
         }
      }

      // No solution possible
      if (lastCharacter == -1)
      {
         System.out.println(-1);
         return;
      }

      // Do the same for the remaining N characters.
      for (int i=1; i<N; i++)
      {
         for (int k=0; k<26; k++)
         {
            int sum = maxSum(N-i-1, k) + Math.abs(lastCharacter-k);
            boolean passed = sum >= K;
            if (i == N-1)
               passed = sum == K;
            if (passed)
            {
               sb.append((char)('a'+k));
               K -= Math.abs(lastCharacter-k);
               lastCharacter = k;
               break;
            }
         }
      }
      if (K != 0) System.out.println("Solution Broken");
      System.out.println(sb);
   }
}