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)

use std::io::stdin;
use std::str::FromStr;
#[allow(dead_code, unused_mut)]
fn read<T: FromStr>() -> T {
    let mut s = String::new();
    stdin().read_line(&mut s).ok();
    s.trim().parse().ok().expect("1")
}
#[allow(dead_code, unused_mut)]
fn read_vec<T: FromStr>() -> Vec<T> {
    read::<String>().split_whitespace()
        .map(|e| e.parse().ok().expect("2"))
        .collect()
}
#[allow(dead_code, unused_mut)]
fn read_two<T: FromStr>() -> (T, T) {
    let mut s = String::new();
    stdin().read_line(&mut s).unwrap();
    let mut x = s.split_whitespace().map(|x| x.parse().ok().unwrap());
    (x.next().unwrap(), x.next().unwrap())
}
#[allow(dead_code, unused_mut)]
fn read_three<T: FromStr>() -> (T, T, T) {
    let mut s = String::new();
    stdin().read_line(&mut s).unwrap();
    let mut x = s.split_whitespace().map(|x| x.parse().ok().unwrap());
    (x.next().unwrap(), x.next().unwrap(), x.next().unwrap())
}
fn main() {
    let (sh, wo) = read_two::<i32>();
    if sh <= wo {
        println!("unsafe");
    } else if sh > wo {
        println!("safe");
    }
}