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 Rust (1.42.0) (judge verdict: Wrong Answer)

    macro_rules! input {
      (source = $s:expr, $($r:tt)*) => {
          let mut iter = $s.split_whitespace();
          let mut next = || { iter.next().unwrap() };
          input_inner!{next, $($r)*}
      };
      ($($r:tt)*) => {
          let stdin = std::io::stdin();
          let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
          let mut next = move || -> String{
              bytes
                  .by_ref()
                  .map(|r|r.unwrap() as char)
                  .skip_while(|c|c.is_whitespace())
                  .take_while(|c|!c.is_whitespace())
                  .collect()
          };
          input_inner!{next, $($r)*}
      };
    }
     
    macro_rules! input_inner {
      ($next:expr) => {};
      ($next:expr, ) => {};
     
      ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
          let $var = read_value!($next, $t);
          input_inner!{$next $($r)*}
      };
     
      ($next:expr, mut $var:ident : $t:tt $($r:tt)*) => {
        let mut $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
      };
    }
     
    macro_rules! read_value {
      ($next:expr, ( $($t:tt),* )) => {
          ( $(read_value!($next, $t)),* )
      };
     
      ($next:expr, [ $t:tt ; $len:expr ]) => {
          (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
      };
     
      ($next:expr, chars) => {
          read_value!($next, String).chars().collect::<Vec<char>>()
      };
     
      ($next:expr, usize1) => {
          read_value!($next, usize) - 1
      };
     
      ($next:expr, $t:ty) => {
          $next().parse::<$t>().expect("Parse error")
      };
    }
     
    pub trait LexicalPermutation {
        /// Return `true` if the slice was permuted, `false` if it is already
        /// at the last ordered permutation.
        fn next_permutation(&mut self) -> bool;
        /// Return `true` if the slice was permuted, `false` if it is already
        /// at the first ordered permutation.
        fn prev_permutation(&mut self) -> bool;
    }
     
    impl<T> LexicalPermutation for [T]
    where
        T: Ord,
    {
        /// Original author in Rust: Thomas Backman <serenity@exscape.org>
        fn next_permutation(&mut self) -> bool {
            // These cases only have 1 permutation each, so we can't do anything.
            if self.len() < 2 {
                return false;
            }
     
            // Step 1: Identify the longest, rightmost weakly decreasing part of the vector
            let mut i = self.len() - 1;
            while i > 0 && self[i - 1] >= self[i] {
                i -= 1;
            }
     
            // If that is the entire vector, this is the last-ordered permutation.
            if i == 0 {
                return false;
            }
     
            // Step 2: Find the rightmost element larger than the pivot (i-1)
            let mut j = self.len() - 1;
            while j >= i && self[j] <= self[i - 1] {
                j -= 1;
            }
     
            // Step 3: Swap that element with the pivot
            self.swap(j, i - 1);
     
            // Step 4: Reverse the (previously) weakly decreasing part
            self[i..].reverse();
     
            true
        }
     
        fn prev_permutation(&mut self) -> bool {
            // These cases only have 1 permutation each, so we can't do anything.
            if self.len() < 2 {
                return false;
            }
     
            // Step 1: Identify the longest, rightmost weakly increasing part of the vector
            let mut i = self.len() - 1;
            while i > 0 && self[i - 1] <= self[i] {
                i -= 1;
            }
     
            // If that is the entire vector, this is the first-ordered permutation.
            if i == 0 {
                return false;
            }
     
            // Step 2: Reverse the weakly increasing part
            self[i..].reverse();
     
            // Step 3: Find the rightmost element equal to or bigger than the pivot (i-1)
            let mut j = self.len() - 1;
            while j >= i && self[j - 1] < self[i - 1] {
                j -= 1;
            }
     
            // Step 4: Swap that element with the pivot
            self.swap(i - 1, j);
     
            true
        }
    }
     
    #[cfg(not(debug_assertions))]
    macro_rules! mydbg {
        ($($arg:expr),*) => {};
    }
     
    macro_rules! echo {
        ($($a:expr),*) => {
              $(println!("{}",$a))*
          }
    }
     
    use std::cmp::Ordering::*;
    #[allow(unused_imports)]
    use std::cmp::{max, min};
    use std::collections::{HashMap, VecDeque};
    use std::io::{stdout, BufWriter, Write};
    use std::mem::swap;
     
    fn main() {
        input! {
            s: i32,
            w: i32,
        }
     
        if w > s {
            echo!("unsafe");
        } else {
            echo!("safe");
        }
    }