almost done1

Crypto/src/ROT13.java

@@ -3,11 +3,13 @@ import static java.lang.Character.isUpperCase;
 import static java.lang.Character.toLowerCase;
 
 public class ROT13  {
-
+    private int shift;
     ROT13(Character cs, Character cf) {
+        this.shift = cs - cf;
     }
 
     ROT13() {
+        shift = 13;
     }