let R() = stdin.ReadLine()

let (|Number|_|) n =
    match System.Int32.TryParse n with
    | true, x -> 
        let inRange = 0 <= x && x <= 12345
        let hasLeadingZero = 
            let raw    = n
            let trimed = 
                match n with
                | "0" -> "0"
                | _   -> n.TrimStart('0')
            raw <> trimed            
        if inRange && not hasLeadingZero then 
            Some(x)
        else 
            None
    | _ -> None
    
let A = R()
let B = R()

match A, B with
| Number x, Number y -> "OK"
| _                  -> "NG"
|> printfn "%s"