let R() = stdin.ReadLine()
let N   = R() |> int
let S   = Array.init N (fun _ -> R())

let modeKey = 
    let lis = 
        S 
        |> Array.map (fun x -> x.Length-2)
        |> Array.groupBy (fun x -> x)                 
    let mode = 
        lis 
        |> Array.maxBy (fun (_,len) -> len)
        |> fun (_,len) -> len

    let ret =
        lis
        |> Array.filter (fun (_,len) -> len = mode)
        |> Array.max
        |> fun (k,_) -> k         
    ret        

modeKey |> printfn "%i"