#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define fi first 
#define se second
#define pi pair<ll,ll> 
#define pii pair<ll,pi>
#define pb push_back
#define mk make_pair
int n;
int main(){ 
  #ifndef ONLINE_JUDGE
	freopen("input.txt","r",stdin);
	freopen("output.txt","w",stdout);
  #endif
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int s,w;
  cin>>s>>w;
  if(s<=w)
  	cout<<"unsafe"<<endl;
  else
  	cout<<"safe"<<endl;
}