import java.util.Scanner

object Main {
  def main(args: Array[String]): Unit = {
    //nextLineとnextを同時に使ったら死ぬ
    val sc = new Scanner(System.in)
    val s, w = sc.nextInt()

    if (s <= w) {
      println("unsafe")
    } else {
      println("safe")
    }
    Console.err.println("Is it WA?")
  }
}
