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::{self, Write};

fn main() {
    let mut stdout = io::stdout();
    let stdin = io::stdin();

    let (s, w) = {
        let mut input = String::new();
        stdin.read_line(&mut input).expect("failed to read line");
        let input: Vec<u32> = input
            .split_whitespace()
            .map(|s| s.parse::<u32>().expect("failed to parse string"))
            .collect();
        (input[0], input[1])
    };

    if w >= s {
        println!("unsafe");
    } else {
        println!("safe");
    }
    stdout.flush().unwrap();
}