using System;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        var inputs = Console.ReadLine()
            .Split(' ')
            .Select(txt => int.Parse(txt))
            .ToList();
        var s = inputs[0];
        var w = inputs[1];
        Console.WriteLine(s <= w ? "unsafe" : "safe");
    }
}