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)

#![allow(unused)]

use std::io::{Read, Stdin, StdinLock};
use std::iter::{FromIterator, Iterator};
use std::str::{FromStr};
use std::string::String;

macro_rules! debug {
    ($($a:expr),*) => {
	eprintln!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
    }
}

struct TokenReader<'a> {
    lock: StdinLock<'a>,
}

impl<'a> TokenReader<'a> {
    fn new(s: &'a Stdin) -> TokenReader<'a> {
        TokenReader { lock: s.lock() }
    }

    fn read_chars<T: FromIterator<char>>(&mut self) -> T {
        self.lock
            .by_ref()
            .bytes()
            .map(|c| c.unwrap() as char)
            .skip_while(|c| c.is_whitespace())
            .take_while(|c| !c.is_whitespace())
            .collect::<T>()
    }

    fn read_str(&mut self) -> String {
        self.read_chars::<String>()
    }

    fn read<T: FromStr>(&mut self) -> T {
        self.read_str().parse().ok().unwrap()
    }
}

//==============================================================================
//
// Problem specific code
//
//==============================================================================

fn main() {
    let sin = std::io::stdin();
    let mut tr = TokenReader::new(&sin);

    let s: i64 = tr.read();
    let w: i64 = tr.read();

    println!("{}", if s <= w { "unsafe" } else { "safe" });
}