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 Ruby (2.7.1) (judge verdict: Accepted)

class InputLine
  def self.to_s
    gets.chomp
  end

  def self.to_i
    InputLine.to_s.to_i
  end
  
  def self.to_f
    InputLine.to_s.to_f
  end

  def self.to_sa
    InputLine.to_s.split(' ')
  end

  def self.to_ia
    InputLine.to_sa.map(&:to_i)
  end
  
  def self.to_fa
    InputLine.to_sa.map(&:to_f)
  end
end

def main(argv)
  (s, w) = InputLine.to_ia

  puts (s > w ? 'safe' : 'unsafe')
end

if self.to_s == 'main' then
  main(ARGV)
end