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 Haskell (GHC 8.8.3) (judge verdict: Accepted)

-- FileName   : 164a
-- CreatedDate: 2020-04-26 20:56:13

import Control.Monad
import Data.List

main = do
   [s,w] <- getIntegerList
   if s > w
      then putStrLn "safe"
      else putStrLn "unsafe"


--------------------------------------------
getIntList        = map (read :: String -> Int) . words <$> getLine
getIntegerList    = map (read :: String -> Integer) . words <$> getLine
getIntegerListN m = map (read :: String -> Integer) <$> replicateM m getLine


base :: Integer
base = 1000000007

plus :: Integer -> Integer -> Integer
plus a b = (a+b) `mod` base

times :: Integer -> Integer -> Integer
times a b = a * b `mod` base

minus :: Integer -> Integer -> Integer
minus a b
   | a < b     = a-b + base
   | otherwise = a-b

power :: Integer -> Integer -> Integer
power n k
   | k == 0         = 1
   | k `mod` 2 == 0 = power (times n n) (k`div`2)
   | otherwise      = times n $! power n (k-1)

inv :: Integer -> Integer
inv n = power n $ base - 2

binom :: Integer -> Integer -> Integer
binom n m
   | (n-m) < m = times (foldr times 1 [m+1..n]) $ inv $ foldr times 1 [1..n-m]
   | otherwise = times (foldr times 1 [n-m+1..n]) $ inv $ foldr times 1 [1..m]