import kotlin.math.*

//private val inp = java.io.File("in")
private val inp = System.`in`
private val reader = inp.bufferedReader()
private val wr = java.io.PrintWriter(System.out.bufferedWriter())

private fun readLn(): String = reader.readLine()
private fun readInt(): Int = readLn().toInt()
private fun readStrs(): List<String> = readLn().split(" ")
private fun readInts(): IntArray = readStrs().map { it.toInt() }.toIntArray()
private fun readChars(): CharArray = readStrs().map { it.single() }.toCharArray()

fun main() {
    val (s, w) = readInts()
    println(if (w >= s) "unsafe" else "safe")
}