#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(long long int i=a; i<b; i++ )
#define REP(i,n) rep(i,0,n)

vector<int> argsort(vector<int> v)
{
	int n = v.size();
	vector<int> indices(n);
	REP(i,n){ indices[i] = i; }

	sort(indices.begin(), indices.end(), [&v](size_t i1, size_t i2) {
        return v[i1] > v[i2];
  });

	return indices;
}

void displayVector(vector<int> v)
{
	int n = v.size();
	REP(i,n){
		cout << v[i] << " " ;
	}
	cout << endl;
}

int main(){
  int S, W; cin >> S, W;
  if(S <= W){ cout << "unsafe" << endl;}
  else{ cout << "safe" << endl; }
  return 0;
}