#include <iostream>
#include <bits/stdc++.h>
#include <numeric> //For gcd()
#define ll long long int
#define all(v) (v).begin(), (v).end()
#define pb push_back
#define fo(i, n) for (int i = 0; i < n; ++i)
#define foe(i, n) for (int i = 1; i <= n; ++i)
#define Fo(i, k, n) for (int i = k; i < n; ++i)
#define FOR(i, a, b) for (int i = (a); i < (b); ++(i))
#define vi vector<int>
#define vll vector<ll>
#define vvl vector<vector<ll>>
#define vpll vector<pair<ll, ll>>
#define MOD 998244353
#define MAX 1024
using namespace std;
using pi = pair<ll, ll>;

int32_t main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	ll s,w;
	cin>> s>> w;
	if(w >= s){
		cout<<"unsafe"<<endl;
	} else cout<<"safe"<<endl;
}