#include <bits/stdc++.h>
#define rep(i,n) for (int i=0;i<(n);i++)
#define adrep(i,s,n) for (int i=(s);i<(n);i++)
using namespace std;
typedef long long ll;

int main(){

  int a,b=0;
  cin>>a>>b;
	
 
  if(a<=b)cout<<"unsafe"<<endl;
  else cout<<"safe"<<endl;

}