#include <bits/stdc++.h>
using namespace std;

int main() {
    long test=1;
    // cin>>test;
    while(test--)
    {
	long i,j,n,a,b,c,d,ans,A,B;
	string s1,s2,s3;
	cin>>a>>b;
	if(b>=a)cout<<"unsafe";
	else cout<<"safe";
	
	
    }
	return 0;
}