let readString() = stdin.ReadLine()
let readStringArray() = stdin.ReadLine().Split(' ');
let readInt() = readString() |> int
let readIntArray() = readStringArray() |> Array.map (fun x -> int x)

let x, a, b = readIntArray() |> fun x -> (x.[0], x.[1], x.[2])
if b - a <= 0 then 
    "delicious"
else if b - a >= x + 1 then 
    "dangerous"
else 
    "safe"
|> printfn "%s"