PROCEDURE ChangeCharToInt(READONLY x: CHAR) : INTEGER =
BEGIN 
   IF x = VAL(ORD('0'),CHAR) THEN 
     RETURN(0);
   END;  
   IF   x >= VAL(ORD('A'), CHAR)  AND  x <= VAL(ORD('Z'), CHAR) THEN
     RETURN(ORD(x) - ORD('A') + 1);
   END;  
   IF   x >= VAL(ORD('a'), CHAR) THEN
     RETURN(-(ORD(x)- ORD('a') + 1)); 
   END;  
   RETURN(99); (* error *)
 END ChangeCharToInt;