#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define fbo find_by_order
#define ook order_of_key

typedef long long ll;
typedef pair<ll,ll> ii;
typedef vector<int> vi;
typedef long double ld;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
    ll s,w;
    cin>>s>>w;
    if(s>w)
        cout<<"safe"<<endl;
    else
        cout<<"unsafe"<<endl;
    return 0;
}
