#include <bits/stdc++.h>
using namespace std;
#define x first
#define y second
#define SZ(x) x.size()
#define POP __builtin_popcount
#define CLZ __builtin_clz
#define CTZ __builtin_ctx
constexpr int INF {INT_MAX};
constexpr float INFF {FLT_MAX};
constexpr long long INFL {LLONG_MAX};
#define float long double
#define int long long

main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.setf(ios::fixed);
	int a,b;
	cin>>a>>b;
	if (b>=a) cout <<"unsafe\n";
	else cout << "safe\n";
	
}
