#include <bits/stdc++.h>
using namespace std;
#define all(c) c.begin(),c.end()
#define init(c) memset(c,0,sizeof c)
#define S second
#define F first
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<ll> vl;
const int N=20000005;
int n,k,x,t,a,b,m;
string s;
vi v;
int main(){

	cin >>a >> b;
	if(b>=a){
		cout << "unsafe";
	}else{
		cout << "safe";
	}

	
	return 0;
}