open System open System.Collections.Generic [] 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())) [] 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 main() = let a = reada int |> Array.sort let mutable ok = true for i in 0 .. 2 do if a.[i] + 1 <> a.[i + 1] then ok <- false if ok then "Yes" else "No" |> puts () // ----------------------------------------------------------------------------------------------------- main() writer.Dispose()