#include <iostream>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <string>
#include <iomanip>
using namespace std;
int main(){
	int s,w;
	cin>>s>>w;
	if(s<=w){
		cout<<"unsafe"<<endl;
	}else{
		cout<<"safe"<<endl;
	}
	return 0;
}
