10 INPUT KEY
 20 INPUT T$
 30 LET C$=""
 40 FOR I=1 TO LEN T$
 50 LET L$=T$(I)
 60 IF L$<"A" OR L$>"Z" THEN GOTO 100
 70 LET L$=CHR$ (CODE L$+KEY)
 80 IF L$>"Z" THEN LET L$=CHR$ (CODE L$-26)
 90 IF L$<"A" THEN LET L$=CHR$ (CODE L$+26)
100 LET C$=C$+L$
110 NEXT I
120 PRINT C$