Imports System

Module practiceA
    Sub Main(ByVal args() As String)
        Dim S, W As Integer
        Dim arr(2) As String
        arr = Split(Console.ReadLine())
        S = arr(0)
        W = arr(1)

        If S > W Then
            Console.Write("safe")

        Else
            Console.Write("unsafe")
        End If

    End Sub
End Module