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: Accepted)

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
template<class T> inline bool chmax(T& a,T b){if(a<b){a=b;return true;}return false;}
template<class T> inline bool chmin(T& a,T b){if(a>b){a=b;return true;}return false;}
const ll INF = 1LL<<60;
const ll M = 1000000007;
ll mpow(ll a,ll b){ll res=1;while(b!=0){if(b&1)res=res*a%M;a=a*a%M;b=b>>1;}return res;}
ll mcomb(ll n,ll k){if(k>n/2)return mcomb(n,n-k);ll res=1;for(ll i=0;i<k;i++){res=res*(n-i)%M;res=res*mpow(k-i,M-2)%M;}return res;}
/*template*/

int main()
{
  ll s,w;cin>>s>>w;
  string ans= s<=w ? "unsafe":"safe";
  cout<<ans<<endl;
  return 0;
}