CLS
OPEN "input.txt" FOR INPUT AS #1
OPEN "output.txt" FOR OUTPUT AS #2
INPUT #1, x$
n = LEN(x$)
REDIM aa(4)
nb$ = ""
ne$ = ""
sk1 = 0
sk2 = 0
sr1 = 0
sr2 = 0
t1 = 0: t2 = 0: t3 = 0: t4 = 0
y$ = ""
FOR i = n TO 1 STEP -1
y$ = y$ + MID$(x$, i, 1)
NEXT i
FOR i = 1 TO n
l = INSTR(i, x$, "[")
IF l = 0 THEN GOTO 20
IF i = 1 THEN sk1 = sk1 + 1: aa(1) = l: i = l ELSE sk1 = sk1 + 1: i = l
NEXT i
20 FOR i = 1 TO n
l = INSTR(i, y$, "]")
IF l = 0 THEN GOTO 30
IF i = 1 THEN sk2 = sk2 + 1: aa(2) = l: i = l ELSE sk2 = sk2 + 1: i = l
NEXT i
30 FOR i = 1 TO n
l = INSTR(i, x$, "(")
IF l = 0 THEN GOTO 40
IF i = 1 THEN sr1 = sr1 + 1: aa(3) = l: i = l ELSE sr1 = sr1 + 1: i = l
NEXT i
40 FOR i = 1 TO n
l = INSTR(i, y$, ")")
IF l = 0 THEN GOTO 50
IF i = 1 THEN sr2 = sr2 + 1: aa(4) = l: i = l ELSE sr2 = sr2 + 1: i = l
NEXT i
50 IF aa(2) = 0 THEN GOTO 60
IF (aa(2) < aa(4) OR aa(4) = 0) THEN GOSUB 100 ELSE GOSUB 200
60 IF aa(4) = 0 THEN GOTO 70
IF (aa(2) > aa(4) OR aa(2) = 0) THEN GOSUB 200 ELSE GOSUB 100
70 IF aa(1) = 0 THEN GOTO 80
   IF (aa(1) > aa(3) OR aa(3) = 0) THEN GOSUB 300 ELSE GOSUB 400
80 IF aa(3) = 0 THEN GOTO 90
   IF (aa(3) < aa(1) OR aa(1) = 0) THEN GOSUB 400 ELSE GOSUB 300
90 i = 1
WHILE MID$(nb$, i, 1) = "[" AND i < LEN(nb$)
i = i + 1
t1 = t1 + 1
WEND
i = 1
WHILE MID$(nb$, i, 1) = "(" AND i < LEN(nb$)
i = i + 1
t2 = t2 + 1
WEND
i = LEN(ne$)
WHILE MID$(ne$, i, 1) = "]" AND i > 1
i = i - 1
t3 = t3 + 1
WEND
i = LEN(ne$)
WHILE MID$(ne$, i, 1) = ")" AND i > 1
i = i - 1
t4 = t4 + 1
WEND


91 IF t1 <> 0 AND t3 <> 0 THEN GOSUB 520
IF t2 <> 0 AND t4 <> 0 THEN GOSUB 540
PRINT #2, nb$; x$; ne$
CLOSE
SYSTEM

100 FOR i = 1 TO sk2
nb$ = nb$ + "["
NEXT i
RETURN

200 FOR i = 1 TO sr2
nb$ = nb$ + "("
NEXT i
RETURN

300 FOR i = 1 TO sk1
ne$ = ne$ + "]"
NEXT i
RETURN

400 FOR i = 1 TO sr1
ne$ = ne$ + ")"
NEXT i
RETURN

520 IF t1 > t3 THEN nb$ = MID$(nb$, t3, LEN(nb$) - t3): ne$ = LEFT$(nb$, LEN(nb$) - t3) ELSE nb$ = MID$(nb$, t3, LEN(nb$) - t1): ne$ = LEFT$(ne$, LEN(ne$) - t1)
RETURN

540 IF t2 > t4 THEN nb$ = MID$(nb$, t4, LEN(nb$) - t4): ne$ = LEFT$(nb$, LEN(nb$) - t4) ELSE nb$ = MID$(nb$, t2, LEN(nb$) - t2): ne$ = LEFT$(ne$, LEN(ne$) - t2)
RETURN