Imports System.Collections
Imports System.Collections.Generic
Imports System.Linq
Imports System.xml
Imports System.xml.Linq

Module Module1
	public sub main()

		dim SW as string() = Console.ReadLine().split(" ")
    dim S as integer = convert.toint32(SW(0))
    dim W as integer = convert.toint32(SW(1))
    if W >= S then 
      console.writeLine("unsafe")
    else
      console.writeLine("safe")
    end if
    
	end sub 
End Module