#include <bits/stdc++.h>
using namespace std;
using ll = long long;
 
#define REPI(i, a, n)	for(ll (i)=(a);(i)<(int)(n);(i++))
#define REP(i,n) REPI(i,0,n)
#define REP1(i,n) for(ll (i)=1;(i)<=(n);(i++))
#define ALL(x) x.begin(), x.end()
#define MAX(x) *max_element(ALL(x))
#define MIN(x) *min_element(ALL(x))
 
struct ProconInit {
	static constexpr int IOS_PREC = 15;
	static constexpr bool AUTOFLUSH = false;
 
	ProconInit() {
		cin.tie(nullptr);
		ios::sync_with_stdio(false);
		cout << fixed << setprecision(IOS_PREC);
		if (AUTOFLUSH)
			cout << unitbuf;
	}
} PROCON_INIT;
 
template<typename T>
int contains(std::vector<T> vec, int number) {
	auto itr = std::find(vec.begin(), vec.end(), number);
	size_t index = std::distance(vec.begin(), itr);
	if (index != vec.size()) { // 発見できたとき
		return 1;
	}
	else { // 発見できなかったとき
		return 0;
	}
}
ll gcd(ll a, ll b) {
	if (a < b)swap(a, b);
	if (a % b == 0)return b;
	return gcd(a % b, b);
}
ll lcm(ll a, ll b) {
	return a / gcd(a, b) * b;
}
ll fact(ll n) {
	ll m;
	if (n == 0) {
		return 1;
	}
	m = fact(n - 1);
	return n * m;
}
 
ll Combination(unsigned long long n, unsigned long long r) {
	if (r * 2 > n) r = n - r;
	uintmax_t dividend = 1;
	uintmax_t divisor = 1;
	for (unsigned int i = 1; i <= r; ++i) {
		dividend *= (n - i + 1);
		divisor *= i;
	}
	return dividend / divisor;
}
 
struct vec {
	ll x, y;
 
	bool operator == (const vec &v) const{
		return x == v.x && y == v.y;
	}
 
};
 
namespace std {
	template<>
	class hash<vec> {
	public:
		size_t operator () (const vec& p) const { return p.x%SIZE_MAX; }
	};
}

int main() {
	int S, W;
	cin >> S >> W;
	cout << (S <= W ? ("unsafe") : ("safe")) << endl;

	return 0;
}