open System
open System.Collections.Generic

[<AutoOpen>]
module Cin =
    let read f = stdin.ReadLine() |> f
    let reada f = stdin.ReadLine().Split() |> Array.map f
    let readChars() = read string |> Seq.toArray
    let readInts() = readChars() |> Array.map (fun x -> Convert.ToInt32(x.ToString()))

[<AutoOpen>]
module Cout =
    let writer = new IO.StreamWriter(new IO.BufferedStream(Console.OpenStandardOutput()))
    let print (s: string) = writer.Write s
    let println (s: string) = writer.WriteLine s
    let inline puts (s: ^a) = string s |> println

let solve() =
    let n = read int
    let s = reada string
    let t = reada string
    seq {
        for i in 0 .. n - 1 do
            if s.[i] <> t.[i] then yield (i + 1, s.[i], t.[i])
    }
    |> Seq.head
    |> fun (i, a, b) ->
        sprintf "%d\n%s\n%s" i a b
    |> puts

[<EntryPoint>]
let main _ =
    try
        solve()
    with e -> printfn "%s" (e.ToString())
    writer.Close()
    0 // return an integer exit code