let n = stdin.ReadLine () |> int

let arr =
    [|
        for _ in 0..n-1 ->
            let [|t; s|] = stdin.ReadLine().Split " "
            int t, s
    |]
    
// let write: (int*string)*(int*string) -> int*string = function
//     | (_, prev), (0, s) -> (0, prev + s)
//     | (_, prev), (1, s) -> (1, s + prev)
//     
// let writeWrap a b =
//     write (a, b)
    

let mutable ans = ""
for t, s in arr do
    match t with
    | 0 -> ans <- ans + s
    | _ -> ans <- s + ans
    
printfn "%s" ans
    
// Array.reduce writeWrap arr |> snd |> printfn "%s"