#include<bits/stdc++.h>
#include <algorithm>
using namespace std;

#define ll long long int 
#define MOD 1000000007
#define sc(a) scanf("%lld",&a)
#define f0(n) for(ll i=0;i<n;i++)
#define f1(n) for(ll i=1;i<=n;i++)
#define pb(v,a) v.push_back(a)
#define pbp(v,a,i) v.push_back(make_pair(a,i)) 
#define srt(v) sort(v.begin(),v.end());

int n,a[300001];

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