open System

let No446 () = 
    let A = Console.ReadLine()
    let B = Console.ReadLine()

    let rec checkNum (S : String) (n : int) =
        if n = S.Length then
            true
        else if n = 0 && S.[n] = '0' && S.Length <> 1 then
            false
        else if S.[n] >= '0' && S.[n] <= '9' then
            checkNum S (n + 1)
        else 
            false
    if checkNum A 0 && checkNum B 0 then
        printfn "OK"
    else
        printfn "NG"

    ()

No446 ()