#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;
const int MR=1e6+10;
typedef long long LL;

int main() {
	int s,w;
	cin>>s>>w;
	if(w>s) printf("unsafe\n");
	else printf("safe\n");
    return 0;
}