В чем ошибка, извините..?

[nassvora]

[Error] Project1.dpr(25): Operator not applicable to this operand type

program Project1;
 
{$APPTYPE CONSOLE}
 
uses
  SysUtils;
var
 cityname: array [0..1120] of string;
 //cityindex: array [0..1120] of Integer;
 f:Text;
 s:string;
 i:Integer;
begin
    { TODO -oUser -cConsole Main : Insert code here }
 Assign(f,'cities.txt');
 Reset(f);
 
 for i:=0 to 1120 do
   Readln(f,cityname[i]);
 
 s:='go';
 while s <> 'exit' do
 begin
   Readln(s);
   if s in cityname then
   begin
     Writeln(s);
   end
   else
   begin
      Writeln('There is no such city! Try again.');
      Readln(s);
   end;
 
 
 end;
 
 Close(f);
 Readln(s);
end.

[Arigato]

Операция in применяется к множествам, а не к массивам (к сожалению).