uses crt;
Function ReadKey: Char;
Var ch: Char;
Begin
repeat
Ch := Crt.ReadKey;
Case Ch Of
#0: Crt.ReadKey;
'a', 'b', 'c': Begin
ReadKey := Ch; Exit;
End;
End;
until false;
End;
begin
writeln(readkey);
end.
???
Ch := Crt.ReadKey;