#include<bits/stdc++.h>
typedef long long int ll;
#define mod 1000000007
#define ln "\n"
#define pb push_back
#define pf push_front
#define mp make_pair
#define pll pair<ll,ll>
#define f first
#define s second
#define fio ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
using namespace std;
int main(){
    fio;
    ll s,w;
    cin>>s>>w;
    if(w>=s)
    cout<<"unsafe";
    else
    cout<<"safe";
    return 0;
}
