#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
using ll = long long;
using P = pair<int,int>;
void Yes() {
    cout << "Yes" << endl;
}
void No() {
    cout << "No" << endl;
}
int main(void) {
    int s, w; cin >> s >> w;
    if(w >= s) cout << "unsafe";
    else cout << "safe";
}
