#include<bits/stdc++.h>
using namespace std;
#define ll int64_t
#define sec second
#define f first
#define pb push_back
#define pf push_front
#define po pop_back
const ll mod=1000000007;
#define fast ios_base::sync_with_stdio(false)
#define vi vector<ll>
#define vii vector< pair<ll,ll> >
#define pi pair<ll,ll>
#define pii pair< pair<ll,ll> ,ll >
#define set set<ll>
#define map map<ll,ll>
#define tostr to_string
#define toint stoi
#define gcd __gcd
ll maxm(ll a,ll b){return a>b?a:b;}
ll minm(ll a,ll b){return a>b?b:a;}
#define max maxm
#define min minm
const ll inf=1e18;


int main()
{
    fast;

  ll s,w;cin>>s>>w;
  if(w>=s)
    cout<<"unsafe"<<endl;
  else
    cout<<"safe"<<endl;
}
