Problem:
Score : 100 points

Problem Statement

There are S sheep and W wolves.

If the number of wolves is greater than or equal to that of sheep, the wolves will attack the sheep.

If the wolves will attack the sheep, print unsafe; otherwise, print safe.

Constraints

1 \leq S \leq 100

1 \leq W \leq 100

Input

Input is given from Standard Input in the following format:

S W

Output

If the wolves will attack the sheep, print unsafe; otherwise, print safe.

Sample Input 1

4 5

Sample Output 1

unsafe

There are four sheep and five wolves. The number of wolves is not less than that of sheep, so they will attack them.

Sample Input 2

100 2

Sample Output 2

safe

Many a sheep drive away two wolves.

Sample Input 3

10 10

Sample Output 3

unsafe

Solution in C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Text;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using static System.Math;
using static System.Console;
using static exMath;
using static exReadLine;


class Program
{
    static void Main(string[] args)
    {
        int S, W;
        intReadLine(out S, out W);
        if(S > W)
        {
            WriteLine("safe");
        }
        else
        {
            WriteLine("unsafe");
        }
    }
}

static class exReadLine
{
    public static void intReadLine(out int a)
    {
        a = int.Parse(ReadLine());
    }
    public static void intReadLine(out int a, out int b)
    {
        int[] input = ReadLine().Split().Select(int.Parse).ToArray();
        a = input[0];
        b = input[1];
    }
    public static void intReadLine(out int a, out int b, out int c)
    {
        int[] input = ReadLine().Split().Select(int.Parse).ToArray();
        a = input[0];
        b = input[1];
        c = input[2];
    }
    public static void intReadLine(out int a, out int b, out int c, out int d)
    {
        int[] input = ReadLine().Split().Select(int.Parse).ToArray();
        a = input[0];
        b = input[1];
        c = input[2];
        d = input[3];
    }

    public static void longReadLine(out long a)
    {
        a = long.Parse(ReadLine());
    }
    public static void longReadLine(out long a, out long b)
    {
        long[] input = ReadLine().Split().Select(long.Parse).ToArray();
        a = input[0];
        b = input[1];
    }
    public static void longReadLine(out long a, out long b, out long c)
    {
        long[] input = ReadLine().Split().Select(long.Parse).ToArray();
        a = input[0];
        b = input[1];
        c = input[2];
    }
    public static void longReadLine(out long a, out long b, out long c, out long d)
    {
        long[] input = ReadLine().Split().Select(long.Parse).ToArray();
        a = input[0];
        b = input[1];
        c = input[2];
        d = input[3];
    }
    
    public static int[] intArrayReadLine()
    {
        return ReadLine().Split().Select(int.Parse).ToArray();
    }

    public static long[] longArrayReadLine()
    {
        return ReadLine().Split().Select(long.Parse).ToArray();
    }

    public static List<int> intListReadLine()
    {
        return ReadLine().Split().Select(int.Parse).ToList();
    }

    public static List<long> longListReadLine()
    {
        return ReadLine().Split().Select(long.Parse).ToList();
    }
}

static class exMath
{
    // 最大公約数
    public static int Gcd(int a, int b)
    {
        if (a < b) return Gcd(b, a);
        while (b != 0)
        {
            var r = a % b;
            a = b;
            b = r;
        }
        return a;
    }
    public static long Gcd(long a, long b)
    {
        if (a < b) return Gcd(b, a);
        while (b != 0)
        {
            var r = a % b;
            a = b;
            b = r;
        }
        return a;
    }

    // 最小公倍数
    public static long Lcm(int a, int b)
    {
        return BigMul(a, b) / Gcd(a, b);
    }
    public static long Lcm(long a, long b)
    {
        return a * b / Gcd(a, b);
    }
}