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 C (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <stdio.h>
void battle(int t_attack, int my_hp); // 戦闘
int main() {
  int a, b, c, d; // 変数宣言
  scanf("%d%d%d%d", &a, &b, &c, &d); // 標準入力
  for(int i=0; a>0&&c>0; i++) { // 戦闘ループ
    if (i%2==0) {
      c-=b; // 高橋君→青木君 : 攻撃
    } else {
      a-=d; // 青木君→高橋君 : 攻撃
    }
  }
  if (a<=0) { // 結果
    printf("No\n");
  } else {
    printf("Yes\n");
  }
  return 0;
}