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: Wrong Answer)

using System;

namespace AtCorder
{
    class ABC164
    {

        static void Main(string[] args)
        {
            var result = A();
            if(result == "")
            {
                return;
            }
            Console.WriteLine(result);
        }
        /*
          羊が S匹、狼がW匹います。
          狼の数が羊の数以上のとき、羊は狼に襲われてしまいます。
          羊が狼に襲われるなら unsafe、襲われないなら safe を出力してください。
         */

        static string A()
        {
            var lines = Console.ReadLine().Split(new char[] {' '});

            var s = int.Parse(lines[0]);
            var w = int.Parse(lines[1]);
            if(s <1 || s >100)
            {
                return "";
            }

            if(w  < 1 || w > 100)
            {
                return "";
            }
            if(s >= w)
            {
                return "safe"; 
            }
            else
            {
                return "unsafe";
            }
        }
    }
}