import java.io.*;
import java.util.*;

import static java.lang.Math.*;
import static java.util.Arrays.*;

public class Main/*Change to Main When Submitting*/ {
    static BufferedReader __in;
    static PrintWriter __out;
    static StringTokenizer input;

    public static void main(String[] args) throws IOException {
        __in = new BufferedReader(new InputStreamReader(System.in));
        __out = new PrintWriter(new OutputStreamWriter(System.out));

        read();
        int S =  nextInt(), W = nextInt();
        println(W >= S ? "unsafe" : "safe");

        close();
    }

    static final int IBIG = 1000000007;
    static final int IMAX = 2147483647;
    static final long LMAX = 9223372036854775807L;
    static void read() throws IOException {input = new StringTokenizer(__in.readLine());}
    static String readLine() throws IOException {return __in.readLine();}
    static int nextInt() {return Integer.parseInt(input.nextToken());}
    static int readInt() throws IOException {return Integer.parseInt(__in.readLine());}
    static long nextLong() {return Long.parseLong(input.nextToken());}
    static void print(String s) {__out.print(s);}
    static void println(String s) {__out.println(s);}
    static void print(Object o) {__out.print(o);}
    static void println(Object o) {__out.println(o);}
    static void printy() {__out.println("Yes");}
    static void printY() {__out.println("YES");}
    static void printn() {__out.println("No");}
    static void printN() {__out.println("NO");}
    static void printyn(boolean b) {__out.println(b ? "Yes" : "No");}
    static void printYN(boolean b) {__out.println(b ? "YES" : "NO");}
    static void println(int... a) {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);}
    static void println(long... a) {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);}
    static void println() {__out.println();}
    static void close() {__out.close();}
} import java.io.*; io.* java import java.util.*; util.* java import static java.lang.Math.*; import static java.lang.Math.*; import static java.lang.Math.*; import static java.util.Arrays.*; import static java.util.Arrays.*; import static java.util.Arrays.*; public class Main/*Change to Main When Submitting*/ {
    static BufferedReader __in;
    static PrintWriter __out;
    static StringTokenizer input;

    public static void main(String[] args) throws IOException {
        __in = new BufferedReader(new InputStreamReader(System.in));
        __out = new PrintWriter(new OutputStreamWriter(System.out));

        read();
        int S =  nextInt(), W = nextInt();
        println(W >= S ? "unsafe" : "safe");

        close();
    }

    static final int IBIG = 1000000007;
    static final int IMAX = 2147483647;
    static final long LMAX = 9223372036854775807L;
    static void read() throws IOException {input = new StringTokenizer(__in.readLine());}
    static String readLine() throws IOException {return __in.readLine();}
    static int nextInt() {return Integer.parseInt(input.nextToken());}
    static int readInt() throws IOException {return Integer.parseInt(__in.readLine());}
    static long nextLong() {return Long.parseLong(input.nextToken());}
    static void print(String s) {__out.print(s);}
    static void println(String s) {__out.println(s);}
    static void print(Object o) {__out.print(o);}
    static void println(Object o) {__out.println(o);}
    static void printy() {__out.println("Yes");}
    static void printY() {__out.println("YES");}
    static void printn() {__out.println("No");}
    static void printN() {__out.println("NO");}
    static void printyn(boolean b) {__out.println(b ? "Yes" : "No");}
    static void printYN(boolean b) {__out.println(b ? "YES" : "NO");}
    static void println(int... a) {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);}
    static void println(long... a) {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);}
    static void println() {__out.println();}
    static void close() {__out.close();}
} Main static BufferedReader __in; __in static PrintWriter __out; __out static StringTokenizer input; input static final int IBIG = 1000000007; IBIG 1000000007 static final int IMAX = 2147483647; IMAX 2147483647 static final long LMAX = 9223372036854775807L; LMAX 9223372036854775807L public static void main(String[] args) throws IOException {
        __in = new BufferedReader(new InputStreamReader(System.in));
        __out = new PrintWriter(new OutputStreamWriter(System.out));

        read();
        int S =  nextInt(), W = nextInt();
        println(W >= S ? "unsafe" : "safe");

        close();
    } main {
        __in = new BufferedReader(new InputStreamReader(System.in));
        __out = new PrintWriter(new OutputStreamWriter(System.out));

        read();
        int S =  nextInt(), W = nextInt();
        println(W >= S ? "unsafe" : "safe");

        close();
    } __in = new BufferedReader(new InputStreamReader(System.in)) __in new BufferedReader(new InputStreamReader(System.in)) __out = new PrintWriter(new OutputStreamWriter(System.out)) __out new PrintWriter(new OutputStreamWriter(System.out)) read() read int S =  nextInt() S nextInt() nextInt W = nextInt(); W nextInt() nextInt println(W >= S ? "unsafe" : "safe") println W >= S ? "unsafe" : "safe" W >= S W S "unsafe" "safe" close() close String[] args args static void read() throws IOException {input = new StringTokenizer(__in.readLine());} read {input = new StringTokenizer(__in.readLine());} input = new StringTokenizer(__in.readLine()) input new StringTokenizer(__in.readLine()) static String readLine() throws IOException {return __in.readLine();} readLine {return __in.readLine();} return __in.readLine(); __in.readLine() __in.readLine __in static int nextInt() {return Integer.parseInt(input.nextToken());} nextInt {return Integer.parseInt(input.nextToken());} return Integer.parseInt(input.nextToken()); Integer.parseInt(input.nextToken()) Integer.parseInt Integer input.nextToken() input.nextToken input static int readInt() throws IOException {return Integer.parseInt(__in.readLine());} readInt {return Integer.parseInt(__in.readLine());} return Integer.parseInt(__in.readLine()); Integer.parseInt(__in.readLine()) Integer.parseInt Integer __in.readLine() __in.readLine __in static long nextLong() {return Long.parseLong(input.nextToken());} nextLong {return Long.parseLong(input.nextToken());} return Long.parseLong(input.nextToken()); Long.parseLong(input.nextToken()) Long.parseLong Long input.nextToken() input.nextToken input static void print(String s) {__out.print(s);} print {__out.print(s);} __out.print(s) __out.print __out s String s s static void println(String s) {__out.println(s);} println {__out.println(s);} __out.println(s) __out.println __out s String s s static void print(Object o) {__out.print(o);} print {__out.print(o);} __out.print(o) __out.print __out o Object o o static void println(Object o) {__out.println(o);} println {__out.println(o);} __out.println(o) __out.println __out o Object o o static void printy() {__out.println("Yes");} printy {__out.println("Yes");} __out.println("Yes") __out.println __out "Yes" static void printY() {__out.println("YES");} printY {__out.println("YES");} __out.println("YES") __out.println __out "YES" static void printn() {__out.println("No");} printn {__out.println("No");} __out.println("No") __out.println __out "No" static void printN() {__out.println("NO");} printN {__out.println("NO");} __out.println("NO") __out.println __out "NO" static void printyn(boolean b) {__out.println(b ? "Yes" : "No");} printyn {__out.println(b ? "Yes" : "No");} __out.println(b ? "Yes" : "No") __out.println __out b ? "Yes" : "No" b "Yes" "No" boolean b b static void printYN(boolean b) {__out.println(b ? "YES" : "NO");} printYN {__out.println(b ? "YES" : "NO");} __out.println(b ? "YES" : "NO") __out.println __out b ? "YES" : "NO" b "YES" "NO" boolean b b static void println(int... a) {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);} println {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);} for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); int i = 0, len = a.length - 1; int i = 0 i 0 len = a.length - 1; len a.length - 1 a.length a a.length 1 i < len i len __out.print(a[i]), __out.print(' '), i++ __out.print(a[i]) __out.print __out a[i] a i __out.print(' ') __out.print __out ' ' i++ i ; __out.println(a[a.length - 1]) __out.println __out a[a.length - 1] a a.length - 1 a.length a a.length 1 int... a a static void println(long... a) {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);} println {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);} for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); int i = 0, len = a.length - 1; int i = 0 i 0 len = a.length - 1; len a.length - 1 a.length a a.length 1 i < len i len __out.print(a[i]), __out.print(' '), i++ __out.print(a[i]) __out.print __out a[i] a i __out.print(' ') __out.print __out ' ' i++ i ; __out.println(a[a.length - 1]) __out.println __out a[a.length - 1] a a.length - 1 a.length a a.length 1 long... a a static void println() {__out.println();} println {__out.println();} __out.println() __out.println __out static void close() {__out.close();} close {__out.close();} __out.close() __out.close __out public class Main/*Change to Main When Submitting*/ {
    static BufferedReader __in;
    static PrintWriter __out;
    static StringTokenizer input;

    public static void main(String[] args) throws IOException {
        __in = new BufferedReader(new InputStreamReader(System.in));
        __out = new PrintWriter(new OutputStreamWriter(System.out));

        read();
        int S =  nextInt(), W = nextInt();
        println(W >= S ? "unsafe" : "safe");

        close();
    }

    static final int IBIG = 1000000007;
    static final int IMAX = 2147483647;
    static final long LMAX = 9223372036854775807L;
    static void read() throws IOException {input = new StringTokenizer(__in.readLine());}
    static String readLine() throws IOException {return __in.readLine();}
    static int nextInt() {return Integer.parseInt(input.nextToken());}
    static int readInt() throws IOException {return Integer.parseInt(__in.readLine());}
    static long nextLong() {return Long.parseLong(input.nextToken());}
    static void print(String s) {__out.print(s);}
    static void println(String s) {__out.println(s);}
    static void print(Object o) {__out.print(o);}
    static void println(Object o) {__out.println(o);}
    static void printy() {__out.println("Yes");}
    static void printY() {__out.println("YES");}
    static void printn() {__out.println("No");}
    static void printN() {__out.println("NO");}
    static void printyn(boolean b) {__out.println(b ? "Yes" : "No");}
    static void printYN(boolean b) {__out.println(b ? "YES" : "NO");}
    static void println(int... a) {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);}
    static void println(long... a) {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);}
    static void println() {__out.println();}
    static void close() {__out.close();}
} public class Main/*Change to Main When Submitting*/ {
    static BufferedReader __in;
    static PrintWriter __out;
    static StringTokenizer input;

    public static void main(String[] args) throws IOException {
        __in = new BufferedReader(new InputStreamReader(System.in));
        __out = new PrintWriter(new OutputStreamWriter(System.out));

        read();
        int S =  nextInt(), W = nextInt();
        println(W >= S ? "unsafe" : "safe");

        close();
    }

    static final int IBIG = 1000000007;
    static final int IMAX = 2147483647;
    static final long LMAX = 9223372036854775807L;
    static void read() throws IOException {input = new StringTokenizer(__in.readLine());}
    static String readLine() throws IOException {return __in.readLine();}
    static int nextInt() {return Integer.parseInt(input.nextToken());}
    static int readInt() throws IOException {return Integer.parseInt(__in.readLine());}
    static long nextLong() {return Long.parseLong(input.nextToken());}
    static void print(String s) {__out.print(s);}
    static void println(String s) {__out.println(s);}
    static void print(Object o) {__out.print(o);}
    static void println(Object o) {__out.println(o);}
    static void printy() {__out.println("Yes");}
    static void printY() {__out.println("YES");}
    static void printn() {__out.println("No");}
    static void printN() {__out.println("NO");}
    static void printyn(boolean b) {__out.println(b ? "Yes" : "No");}
    static void printYN(boolean b) {__out.println(b ? "YES" : "NO");}
    static void println(int... a) {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);}
    static void println(long... a) {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);}
    static void println() {__out.println();}
    static void close() {__out.close();}
} Main
import java.io.*;
import java.util.*;

import static java.lang.Math.*;
import static java.util.Arrays.*;

public class Main/*Change to Main When Submitting*/ {
    static BufferedReader __in;
    static PrintWriter __out;
    static StringTokenizer input;

    public static void main(String[] args) throws IOException {
        __in = new BufferedReader(new InputStreamReader(System.in));
        __out = new PrintWriter(new OutputStreamWriter(System.out));

        read();
        int S =  nextInt(), W = nextInt();
        println(W >= S ? "unsafe" : "safe");

        close();
    }

    static final int IBIG = 1000000007;
    static final int IMAX = 2147483647;
    static final long LMAX = 9223372036854775807L;
    static void read() throws IOException {input = new StringTokenizer(__in.readLine());}
    static String readLine() throws IOException {return __in.readLine();}
    static int nextInt() {return Integer.parseInt(input.nextToken());}
    static int readInt() throws IOException {return Integer.parseInt(__in.readLine());}
    static long nextLong() {return Long.parseLong(input.nextToken());}
    static void print(String s) {__out.print(s);}
    static void println(String s) {__out.println(s);}
    static void print(Object o) {__out.print(o);}
    static void println(Object o) {__out.println(o);}
    static void printy() {__out.println("Yes");}
    static void printY() {__out.println("YES");}
    static void printn() {__out.println("No");}
    static void printN() {__out.println("NO");}
    static void printyn(boolean b) {__out.println(b ? "Yes" : "No");}
    static void printYN(boolean b) {__out.println(b ? "YES" : "NO");}
    static void println(int... a) {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);}
    static void println(long... a) {for(int i = 0, len = a.length - 1; i < len; __out.print(a[i]), __out.print(' '), i++); __out.println(a[a.length - 1]);}
    static void println() {__out.println();}
    static void close() {__out.close();}
}