#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> pi;
typedef pair<int,int> vi;

#define F first
#define S second
#define PB push_back
#define MK make_pair
#define REP(i, a, b) for (int i=a; i < b; i++)


bool sort_by(vi c, vi d){
	return c.S < d.S;
}

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

}
