10 LET[0],1,2,4,5,10
20 S=4
30 F=-1:L=0:R=4
40  M=(L+R)/2
50  IF [M]=S THEN F=M:GOTO 80
60  IF [M]<S THEN L=M+1 ELSE R=M-1
70  IF L<=R THEN GOTO 40
80 PRINT "FIND=";F
