#include<bits/stdc++.h>
#pragma GCC optimize("Ofast")
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define endl "\n"
#define sz(u) (int)(u.size())
typedef long long ll;
using namespace std;
void solve(){
int a,b;
    cin>>a>>b;
    if(a<b)
        cout<<"unsafe";
    else
        cout<<"safe";
}
int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    solve();

}
