#include<bits/stdc++.h>
#define ll  long long  
#define pb push_back
#define fi first
#define se second
using namespace std;
//vector<ll> v[1000001];
void dfs(ll u,ll p)
{
	
}
bool comp(const pair<ll,ll>&a,const pair<ll,ll> &b)
{
	return (a.second < b.second);
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
 int tc=1;
//cin>>tc;
ll cas=1;
 while(tc--)
 {
	ll s,w;
	cin>>s>>w;
	if(w>=s)
	cout<<"unsafe";
	else
	cout<<"safe";
	cout<<"\n"; 
 } 
}
