#include<bits/stdc++.h>
#include<bits/stdc++.h>
#include <vector>
#define ll long long int
#define ve vector<int>
#define vell vector<ll>
#define pb push_back
#define mod 998244353
using namespace std;
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
int s,w;cin>>s>>w;
if(w>=s)
{
	cout<<"unsafe";
}
else
{
	cout<<"safe";
}


}
 