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)

struct Read<R: std::io::BufRead> {
    stdin: R,
    v: Vec<String>,
    i: usize,
}
impl<R:std::io::BufRead> Read<R> {
    pub fn new(stdin: R) -> Self {
        Read{
            stdin: stdin,
            v: Vec::new(),
            i: 0,
        }
    }
    pub fn read_until<T: std::str::FromStr>(&mut self) -> T {
        if self.i == self.v.len() {self.read_line();}
        let elem = &self.v[self.i];
        self.i += 1;
        elem.parse().unwrap_or_else(|_| panic!())
    }
    pub fn read_line(&mut self) {
        self.i = 0; self.v.clear();
        let mut buf = String::new();
        self.stdin.read_line(&mut buf).unwrap();
        let buf = buf.trim().to_owned();
        let mut ws = buf.split_whitespace();
        loop {
            let x = ws.next();
            if x.is_none() {break;}
            let x = x.unwrap().to_owned();
            self.v.push(x);
        }
    }
    #[allow(dead_code)]
    pub fn read_i32(&mut self) -> i32 {
        if self.i == self.v.len() {self.read_line();}
        let elem = self.v[self.i].parse().unwrap();
        self.i += 1;
        elem
    }
    #[allow(dead_code)]
    pub fn read_string(&mut self) -> String {
        if self.i == self.v.len() {self.read_line();}
        let elem = &self.v[self.i];
        self.i += 1;
        elem.to_owned()
    }
}
fn main() {
    use std::io;
    let stdin = io::stdin();
    let stdin = io::BufReader::new(stdin.lock());
    let read = Read::new(stdin);
    solve(read);
}

fn solve<R: std::io::BufRead>(mut r: Read<R>) {
    let s:i32 = r.read_until();
    let w:i32 = r.read_until();
    println!("{}", if s <= w {
        "unsafe"
    }else{
        "safe"
    });
}