#include <bits/stdc++.h>
typedef long long int ll;
#define rep(i,n) for (int i = 0; i< (n); i++)
#define Rep(i,n,m) for (int i = (n); i< (m); i++)
#define Sort(a) sort(a.begin(), a.end())
#define Reverse(a) reverse(a.begin(), a.end())
const int INF = 1e9;
const ll MOD = 1000000007;
const ll LINF = 1e18;
using namespace std;



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

