#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef long double ld;

#define rep(i,s,n) for(ll (i)=(s);(i)<(n);(i)++)
#define repd(i,s,n) for(ll (i)=(n-1);(i)>=(s);(i)--)
#define all(x) x.begin(),x.end()
#define size(x) ((ll)(x).size()
#define PB push_back

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

   return 0;
}
