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 PHP (7.4.4) (judge verdict: Accepted)

<?php
/**
 * 標準出力　1行
 */
// 標準入力からの入力値を変数に代入します
$single_line_input = fgets(STDIN);
// 取得した入力値を半角スペースで分解します
$array = explode(" ", $single_line_input );
// 単一行の入力の場合はこれだけで各入力値が配列の要素として使えます


$num_sheep = $array[0];
$num_wolf = $array[1];

if((int)$num_wolf >= (int)$num_sheep){
    print('unsafe');
}else{
    print('safe');
}