#include"bits/stdc++.h"

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define REP(i, n) for (int i = 1; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
using ll = long long;

using namespace std;
int main(){
	int S, W;
	cin >> S >> W;
	if (S <= W) {
		cout << "unsafe" << endl;
	}
	else {
		cout << "safe" << endl;
	}
}
