let solve N M Ia =
(Array.zeroCreate N, Ia)
||> Array.fold (fun Ga (a,b) -> Ga.[a-1]<-1+Ga.[a-1]; Ga.[b-1]<-1+Ga.[b-1]; Ga)
|> Array.forall (fun x -> x%2=0)
|> fun b -> if b then "YES" else "NO"
let N,M = stdin.ReadLine().Split() |> Array.map int |> (fun x -> x.[0],x.[1])
let Ia = Array.init M (fun _ -> stdin.ReadLine().Split() |> Array.map int |> fun x -> x.[0],x.[1])
solve N M Ia |> stdout.WriteLine