#include <bits/stdc++.h>
#define _GLIBCXX_DEBUG
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rrep(i, n) for (int i = 1; i < (n+1); ++i)
using namespace std;
using ll = long long;
const int INF = +100100100;
typedef pair<int,int> P;
const ll MO = 1000000007;

int main(){
    int s,w;
    cin >> s >> w;
    if(w>=s)cout<<"unsafe"<<endl;
    else cout << "safe"<<endl;
    return 0;
}