#include<cstdio>
#include<cmath>
#include<climits>
#include<algorithm>
#include<sstream>
#include<iostream>
#include<string>
#include<vector>
#include<queue>
#include<stack>
#include<unordered_set>
#include<unordered_map>
#include<set>
#include<map>
#include<list>

using namespace std;

#define in(s) cin >> s
#define out(s) cout << s << endl
#define rep(i,n) for(int i=0; i<n; i++)
#define rept(i,a,b) for(int i=a; i<b; i++)
#define ll long long
#define MOD 1000000007

#define IMIN INT_MIN;
#define IMAX INT_MAX;


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

	return 0;
}
