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: Accepted)

        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");
            }
        }