var
 a,b:Integer;
 c:real;
 pilih:Integer;
 z:DateDelta;

begin
 // try
c:=0;
     Writeln('========Belajar  case==========');
     Writeln('***pilih operasi***');
     Writeln('pilihan 1 Penjumlahan');
     Writeln('pilihan 2 Pengurangan');
     Writeln('pilihan 3 Pengurangan');
     Writeln('pilihan 4 Perkalian');
Writeln('');
Writeln('');
    Write('masukkan bilangan 1 = ');Read(a);
    Write('masukkan bilangan 2 = ');Read(b);
    Write('masukkan pilihan = '); Read(pilih);
      case pilih of
      1:c:=a+b;
      2:c:=a-b;
      3:c:=a*b;
      4:c:=a/b;
      end;
    Writeln('hasil nya adalah = ',c:0:2);
  Writeln(DateDelta(z));
  {except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);}
  //end;
end.