#include <bits/stdc++.h>
using namespace std;
void __print(int x) {cout << x;}
void __print(long x) {cout << x;}
void __print(long long x) {cout << x;}
void __print(unsigned x) {cout << x;}
void __print(unsigned long x) {cout << x;}
void __print(unsigned long long x) {cout << x;}
void __print(float x) {cout << x;}
void __print(double x) {cout << x;}
void __print(long double x) {cout << x;}
void __print(char x) {cout << '\'' << x << '\'';}
void __print(const char *x) {cout << '\"' << x << '\"';}
void __print(const string &x) {cout << '\"' << x << '\"';}
void __print(bool x) {cout << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cout << '{'; __print(x.first); cout << ','; __print(x.second); cout << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cout << '{'; for (auto &i: x) cout << (f++ ? "," : ""), __print(i); cout << "}";}
void _print() {cout << "\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cout << ", "; _print(v...);}
#define debug(x...) cout << #x << " = "; _print(x)
typedef long long ll; typedef vector<int> vi; typedef vector<ll> vll;
#define rep(i,a,b) for (int i = (a); i < (b); ++i)
#define per(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define all(x) begin(x), end(x)
#define mp make_pair 
#define pb push_back
#define ff first
#define ss second
#define fast ios_base::sync_with_stdio(NULL);cin.tie(NULL);cout.tie(NULL)
#define ld long double

int solve(){
	int s, w;
	cin>> s>> w;
	if(w >= s)
		cout<< "unsafe\n";
	else
		cout<< "safe\n";	
	return 0;
}
 
int main()
{
	fast;
	int t = 1;
	//cin>> t;
	while(t--){  
		solve();
	}
	return 0;
}
//upper_bound returns an iterator pointing to the 
//first element in the range [first,last) which has a value greater than ‘val’