PROGRAM tasks            ! illustrate use of subroutines
! note how variables are passed
CALL initial(x,y)                 ! initialize variables
CALL add(x,y,sum)                 ! add two variables
CALL multiply(x,y,product)
PRINT "sum ="; sum, "product ="; product
END                               ! end of main program

SUB initial(x,y)
    INPUT x
    INPUT y
END SUB

SUB add(x,y,sum)
    LET sum = x + y
END SUB

SUB multiply(x,y,product)
    LET product = x*y
END SUB