#include<algorithm>
#include<iostream>
#include<vector>
#include<string>
#include<queue>
#include<stack>
#include<cmath>
#include<list>
#include<set>
#include<map>

using namespace std;
long long MOD = 1000000007LL;
#undef INT_MIN
#undef INT_MAX
#define INT_MIN -2147483648
#define INT_MAX 2147483647
#define endl "\n"

int main() {
	int s, w;
	cin >> s >> w;

	cout << (w < s ? "safe" : "unsafe") << endl;

	return 0;
}

