Case Contol-Menu Control In Cobol

IDENTIFICATION DIVISION.
PROGRAM-ID. TESTPROGRAM.
ENVIRONMENT DIVISION.
DATA DIVISION.
WORKING-STORAGE SECTION.
77 NUM1 PICTURE 9 VALUE ZEROS.
77 NUM2 PIC 9 VALUE ZERO.
77 ADDRES PIC 99 VALUE ZEROS.
77 MULRES PIC 99 VALUE ZEROS.
77 SUBRES PIC 9 VALUE ZEROS.
77 DIVRES PIC 9V99 VALUE ZEROS.
77 CH PIC 9.
PROCEDURE DIVISION.
MAINPARA.
DISPLAY " ENTER FIRST NUMBER : ".
ACCEPT NUM1.
DISPLAY " ENTER SECOND NUMBER : ".
ACCEPT NUM2.
DISPLAY "-----------------------".
DISPLAY " MENU ".
DISPLAY "-----------------------".
DISPLAY " 1 --> ADDITION ".
DISPLAY " 2 --> SUBTRACTION ".
DISPLAY " 3 --> MULTIPLICATION ".
DISPLAY " 4 --> DIVISION ".
DISPLAY " 0 --> EXIT ".
DISPLAY "-----------------------".
DISPLAY " ENTER YOUR CHOICE : ".
ACCEPT CH.
IF CH = 1 GO TO ADDPARA.
IF CH = 2 GO TO SUBPARA.
IF CH = 3 GO TO MULPARA.
IF CH = 4 GO TO DIVPARA.
IF CH = 0 GO TO EXIPARA.

ADDPARA.

COMPUTE ADDRES = NUM1 + NUM2.
DISPLAY " ADDITION RESULT :", ADDRES.
GO TO MAINPARA.
SUBPARA.
COMPUTE SUBRES = NUM1 - NUM2.
DISPLAY " SUBTRACTION RESULT : ", SUBRES.
GO TO MAINPARA.
MULPARA.
MULTIPLY NUM1 BY NUM2 GIVING MULRES.
DISPLAY " MULTIPLICATION RESULT : ", MULRES.
GO TO MAINPARA.
DIVPARA.
COMPUTE DIVRES = NUM1 / NUM2.
DISPLAY " DIVISION RESULT : ", DIVRES.
GO TO MAINPARA.

EXIPARA.
STOP RUN.