//code by parshuram_84
#include <bits/stdc++.h>
#define mod 1000000007
#define pii pair<int,int>
#define pll pair<long long,long long>
#define IOS std::ios::sync_with_stdio(false); cin.tie(NULL);cout.tie(NULL);cout.precision(dbl::max_digits10);
#define pb push_back
#define mod 1000000007 //998244353
#define ll long long
#define vi vector<int>
#define vll vector<long long>
#define vp vector<pair<long long,long long>>
#define vpp vector<pair<pair<long long,long long>,long long>>
using namespace std;

int main() {
	int s,w;
	cin>>s>>w;
	if(w>=s) cout<<"unsafe";
	else cout<<"safe";
	return 0;
}