HI,
If the city id's are comming as string split the data and saved in to one dynamic table and pasing as parameter
Declare @TempSource as table (Sno int identity(1,1),Inputvalues varchar(50))
insert into @TempSource(Inputvalues) values('5')
insert into @TempSource(Inputvalues) values('4')
insert into @TempSource(Inputvalues) values('6')
Declare @TempData as table (Sno int identity(1,1),CityName varchar(50),CityID varchar(50))
insert into @TempData(CityName,CityID) values('City1','1')
insert into @TempData(CityName,CityID) values('City2','2')
insert into @TempData(CityName,CityID) values('City4','4')
insert into @TempData(CityName,CityID) values('City6','6')
select * from @TempData
where CityID in (select Inputvalues from @TempSource)