program phone;

        {This program determines where in Mongolia you are calling when you
         enter in an area code and the first three digits of the phone number.}

        {It is a good example of how to use if, then, else statements which
         are nestled inside of other if, then else statements.}

        {Please note : formating is very important and you will be marked on it!}


uses
    WinCRT;

var
   AreaCode, FirstThree:Integer;

begin

     Write ('Please enter the area code of where you are calling : ');
     Readln (AreaCode);
     Write ('Please enter the first three digits of the phone # : ');
     Readln (FirstThree);

     if (AreaCode>=200) and (AreaCode<500) {a number between 200 and 499}
        then
            begin
                 if (FirstThree>=500) and (FirstThree<900) {first three is a number between 500 and 899}
                 then
                     begin
                          Writeln ('You are calling E. Mongolia.');
                          Writeln ('The area code there is ', AreaCode);
                     end
                 else  {if first three is any other number besides 500 - 899}
                     begin
                          Writeln ('You are calling W. Mongolia.');
                          Writeln ('The area code there is ', AreaCode);
                     end;
            end
     else
         if(FirstThree < 800) or (FirstThree >= 900)
         then
             begin
                  writeln ('You are calling N. Mongolia');
                  writeln ('The area code there is ', AreaCode);
             end
         else
             begin
                  writeln ('You are calling S. Mongolia');
                  writeln ('The area code there is ', AreaCode);
             end;
end.


    {Make sure that you can trace this program and understand it, you will need
     to know how to do this to write your posneg.pas, posneg0.pas and telegram.pas
     programs!  Good luck.  I will be back next week if you require extra help.}