I don't know what programming language you are using, but here is an example that should work for you
DECLARE FUNCTION checkamt(lp AS INTEGER) AS INTEGER
DECLARE SUB checknums()
GLOBAL flag AS INTEGER
GLOBAL amt() AS INTEGER
'================================================= ====
FUNCTION PBMAIN () AS LONG
DIM flag AS GLOBAL INTEGER
DIM amt(2) AS GLOBAL INTEGER
DIM I AS INTEGER
DIM response AS STRING, a AS STRING,a1 AS STRING
FOR i=1 TO 2
a$="Amount "+STR$(i)
response$=INPUTBOX$(a$,a1)
'option here: call sub to check if valid number input
amt(i)=VAL(response$)
flag=checkamt(i)
IF flag<>1 THEN
MSGBOX "Amount not within valid range":EXIT FUNCTION
ELSE
END IF
NEXT i
'flag=1 for both numbers, check status of number value
CALL checknums()
END FUNCTION
'================================================= =====
'SUBROUTINES/FUNCTIONS
'=================check amt
FUNCTION checkamt(lp AS INTEGER) AS INTEGER
DIM I AS INTEGER
I=lp
SELECT CASE amt(i)
CASE 11 TO 99
flag=1
CASE ELSE
flag=0
END SELECT
Checkamt=flag
END FUNCTION
'=================check numbers
SUB checknums()
DIM I AS INTEGER, greater AS INTEGER
DIM message AS STRING
Msg$="":greater=0
IF amt(1)>amt(2) THEN
greater=1
ELSEIF amt(1)=amt(2) THEN
greater=0
ELSE
greater=2
END IF
SELECT CASE greater
CASE 0
msg$="Amounts are equal "+STR$(amt(1))+" and "+STR$(amt(2))
CASE 1
msg$="Amount 1:("+STR$(amt(1))+") is greater than amount 2:("+STR$(amt(2))+")"
CASE 2
msg$="Amount 2: ("+STR$(amt(2))+") is greater than amount 1: ("+STR$(amt(1))+")"
CASE ELSE
msg$="Unknown error in amount value"
END SELECT
MSGBOX msg$
END SUB