import java.util.Hashtable;

 public class T035 {

     public static void main(String[] args) {

         FirstNotRepeatingChar("abaccdeff");

     }

     public static char FirstNotRepeatingChar(String pString) {

         Hashtable t = new Hashtable();

         int tableSize = 256;

         for (int i = 0; i < tableSize; i++) {

             t.put(i, 0);

         }

         for (int i = 0; i < pString.length(); i++) {

             int key = pString.charAt(i);

             int value = (Integer) t.get(key);

             t.remove(key);

             t.put(key, ++value);

         }

         int i;

         for (i = 0; i < pString.length(); i++) {

             int key = pString.charAt(i);

             int value = (Integer) t.get(key);

             if (value == 1) {

                 System.out.println(pString.charAt(i));

                 break;

             }

         }

         if (i == pString.length()) {

             System.out.println("none");

         }

         return 0;

     }

 }