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: Runtime Error)

using System;
using System.Linq;
class Program
{
    static void Main(string[] args)
    {
        int[] num = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
        int A, B, C, D;
     
        A = num[0];
        B = num[1];
        C = num[2];
        D = num[3];


        while (A < 0 || C < 0)
        {
            C -= B;
            if (C <= 0)
            {
                Console.WriteLine("Yes");
            }
            else
            {
                A -= D;
                if (A <= 0)
                {
                    Console.WriteLine("No");
                }
            }
        }

    }
}