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_imports)]
use std::cmp;
use std::collections::*;
use std::io::*;
use std::mem::swap;
#[allow(dead_code)]
struct Io<'a> {
    r: BufReader<StdinLock<'a>>,
    w: BufWriter<StdoutLock<'a>>,
    buf: VecDeque<String>,
    buf_str: String,
}
#[allow(dead_code)]
impl<'a> Io<'a> {
    fn r<T: std::str::FromStr>(&mut self) -> T {
        if self.buf.len() == 0 {
            self.r.read_line(&mut self.buf_str).unwrap();
            for w in self.buf_str.split_whitespace() {
                self.buf.push_back(w.to_owned());
            }
            self.buf_str.clear();
        }
        self.buf
            .pop_front()
            .unwrap()
            .parse()
            .unwrap_or_else(|_| panic!())
    }
    fn r_s(&mut self) -> String {
        if self.buf.len() == 0 {
            self.r.read_line(&mut self.buf_str).unwrap();
            for w in self.buf_str.split_whitespace() {
                self.buf.push_back(w.to_owned());
            }
            self.buf_str.clear();
        }
        self.buf.pop_front().unwrap()
    }
    fn w<T: std::fmt::Display>(&mut self, v: T) {
        write!(self.w, "{}", v).unwrap();
    }
    fn wl<T: std::fmt::Display>(&mut self, v: T) {
        writeln!(self.w, "{}", v).unwrap();
    }
    fn iter<'b, T: std::str::FromStr>(&'b mut self) -> IoIter<'a, 'b, T> {
        IoIter {
            io: self,
            p: std::marker::PhantomData,
        }
    }
}
#[allow(dead_code)]
struct IoIter<'a: 'b, 'b, T: std::str::FromStr> {
    io: &'b mut Io<'a>,
    p: std::marker::PhantomData<T>,
}
#[allow(dead_code)]
impl<'a, 'b, T: std::str::FromStr> Iterator for IoIter<'a, 'b, T> {
    type Item = T;
    fn next(&mut self) -> Option<T> {
        Some(self.io.r())
    }
}
fn main() {
    let stdin = stdin();
    let stdout = stdout();
    let r = BufReader::new(stdin.lock());
    let w = BufWriter::new(stdout.lock());
    let mut io = Io {
        r,
        w,
        buf: VecDeque::new(),
        buf_str: String::new(),
    };
    problem(&mut io);
}

fn problem(io: &mut Io) {
    let s: usize = io.r();
    let w: usize = io.r();
    if w >= s {
        io.wl("unsafe");
    } else {
        io.wl("safe");
    }
}