Using Select Case Construct | Fortran

PROGRAM select_case
IMPLICIT NONE
INTEGER::ch

REAL::a,b,res


PRINT *, '============================================'
PRINT *, 'PROGRAM TO UNDERSTAND SELECT CASE [ BY WWW.BOTTOMSCIENCE.COM ]'
PRINT *, '============================================'

PRINT *,'ENTER THE FIRST NUMBER FOR CALCULATION'
READ(*,*)a
PRINT *,'ENTER THE SECOND NUMBER FOR CALCULATION'
READ(*,*)b
PRINT *,'ENTER CHOICE 1. ADDITION 2. SUBTRACTION 3.MULTIPLICATION 4.DIVISION'
READ(*,*)ch

SELECT CASE(ch)

CASE(1)
res=a+b
PRINT *,'ADDITION IS - ',res

CASE(2)
res=a-b
PRINT *,'SUBTRACTION IS - ',res

CASE(3)
res=a*b
PRINT *,'MULTIPLICATION IS - ',res

CASE(4)
res=a/b
PRINT *,'DIVISION IS - ',res

CASE default
PRINT *,'WRONG CHOICE'

END SELECT

END PROGRAM