Program Codebreak;
{Program created by Philip Smith}
{Program allows user to enter an Integer in the range 100-999}
{The number is tested for integer, and must match the security number}
{A valid number is allowed entry}

Uses WinCrt;
Var
   strStart_Num         :String;        {Start number to be validated into integer}
   strEntry_Num         :String;        {System entry number to be validated into integer}
   intError_Start       :Integer;       {Error code for start number}
   intError_Entry_Num   :Integer;       {Error code for system entry number}
   intStart_Num         :Integer;       {Start number after validation}
   intEntry_Num         :Integer;

Begin
    Write('Keypad entry');
    GoToXY(1,2);Write('Please enter your number ');
    Readln(strStart_Num);

    Val(strStart_Num,intStart_Num,intError_Start);

    IF (intStart_Num >= 99) And (intStart_Num < 999)
        Then
            Begin
                GoToXY(1,3);Write('Please enter your encrypted number ');
                Readln(strEntry_Num)
            End
        Else
            Begin
                 GoToXY(1,3);Write('Entry code not correct, error code ',intError_Start)
            End;

    Val(strEntry_Num,intEntry_Num,intError_Entry_Num);

    IF intError_Entry_Num <> 0
         Then
             Begin
                 GoToXY(1,4);Write('Code cannot be accepted, error code ',intError_Entry_Num)
             End
         Else
             Begin
                  GoToXY(1,4);Write('Entry code is being processed')
             End;

    IF intEntry_Num = intStart_Num*2+5
         Then
             Begin
                  GoToXY(1,5);Write('Code is correct, you are granted access to the system')
             End
         Else
             Begin
                  GoToXY(1,5);Write('Code is NOT correct, access denied')
             End;

    GoToXY(1,6);Write('Program is closing');
    Readln;

DoneWinCrt;
End.