#include<bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize ("-ffloat-store")  
#pragma GCC optimize ("-fno-defer-pop")
typedef long long int ll; 
typedef long double ld; 

int main()
{	
    std::ios_base::sync_with_stdio(0);
	  cin.tie(0);
	  cout.tie(0);
    
    ll s,w;
    cin>>s>>w;

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

}