#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)
typedef long long ll;
typedef pair<int,int>P;
#define MAX 1e9
struct edge{int to,cost;};

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