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# (Mono-csc 3.5.0) (judge verdict: Accepted)

using System;
using static System.Console;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;

namespace Atcoder_Answer
{
    class Program
    {
        const Int32 mod = 1000000007;

        static void Main(string[] args)
        {
            string[] Reader = ReadLine().Split(' ');
            int S = int.Parse(Reader[0]);
            int W = int.Parse(Reader[1]);

            if (W >= S) WriteLine("unsafe");
            else WriteLine("safe");
        }
    }

    public static class Extension
    {
        #region 拡張:bool
        #region キャスト関連
        public static int ToInt(this bool Bool)
        {
            if (Bool) return 1;
            else return 0;
        }

        public static string ToString(this bool Bool, string TrueStr, string FalseStr)
        {
            if (Bool) return TrueStr;
            else return FalseStr;
        }
        #endregion
        #endregion

        #region 拡張:int
        #region キャスト関連
        public static char ToAlphaBets(this int Base) => (char)Base;
        #endregion
        #endregion

        #region 拡張:char
        #region 変換関連
        public static char NextAlpha(this char Char) => (char)((Char) + 1); //次の文字を取得
        #endregion
        #endregion

        #region 拡張:int[]
        public static long Sum(this int[] Array)
        {
            int Ret = 0;
            for (int loop = 0; loop < Array.Length; loop++) Ret += Array[loop];
            return Ret;
        }
        #endregion

        #region 拡張: string
        public static string Multi(this string THIS, int Value)
        {
            string RetValue = "";

            for (int loop = 0; loop < Value; loop++) RetValue += THIS;

            return RetValue;
        }
        #endregion

        #region 拡張: List<string>
        public static string Sum(this List<string> THIS, string Split)
        {
            string RetValue = "";

            for (int loop = 0; loop < THIS.Count; loop++)
            {
                RetValue += THIS[loop];
            }

            return RetValue;
        }
        #endregion
    }
}