Triangle 3rd Angle

@ECHO OFF
:DATAIN
SET /P a="First Angle: "
SET /P b="Second Angle: "
SET /A a1 = a
SET /A b1 = b
IF %a%==exit GOTO EXIT
IF %a1% NEQ %a% GOTO DATAIN
IF %b1% NEQ %b% GOTO DATAIN
SET /A INVAL = a1 + b1
IF %INVAL% GTR 179 GOTO ERRORDATA1
SET /A OUTVAL = 180 - INVAL
ECHO A triangle with angles of %a% degrees and %b% degrees will have a third angel of %OUTVAL% degrees.
GOTO EXIT
:ERRORDATA1
ECHO The values you provided (%a% and %b%) do not result in a valid triangle.
:EXIT