10 LET X$="1223334444"
 20 LET U$=""
 30 FOR I=1 TO LEN X$
 40 LET K=0
 50 FOR J=1 TO LEN U$
 60 IF U$(J)=X$(I) THEN LET K=K+1
 70 NEXT J
 80 IF K=0 THEN LET U$=U$+X$(I)
 90 NEXT I
100 DIM R(LEN U$)
110 FOR I=1 TO LEN U$
120 LET C=0
130 FOR J=1 TO LEN X$
140 IF U$(I)=X$(J) THEN LET C=C+1
150 NEXT J
160 LET R(I)=C/LEN X$*LN (C/LEN X$)/LN 2
170 NEXT I
180 LET E=0
190 FOR I=1 TO LEN U$
200 LET E=E-R(I)
210 NEXT I
220 PRINT E