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)

fn main() {
    // s w
    let s = {
        let mut s = String::new(); // バッファを確保
        std::io::stdin().read_line(&mut s).unwrap(); // 一行読む。失敗を無視
        s.trim_right().to_owned() // 改行コードが末尾にくっついてくるので削る
    };

    let (s, w) = {
        let mut ws = s.split_whitespace(); // 空白区切りの単語に分解する
        let n: i32 = ws.next().unwrap().parse().unwrap(); // イテレータから値を取り出して整数に
        let m: i32 = ws.next().unwrap().parse().unwrap();
        (n, m)
    };

    if s > w {
        println!("safe");
        return;
    }

    println!("unsafe");
}