#include <iostream>
#include<sstream>
#include<string>
#include<vector>
#include <cmath>
#include <limits>
#include <queue>
#include<algorithm>
#include<cstring>
#include <cstdlib>
#include <cstdio>
#include <set>
#include <iomanip>
#include <map>
#include <stack>
#include <memory>
#include <numeric>
#include <type_traits>
 
using namespace std;
 
#define rep(i,n) for (int (i)=0;(i)<(n);i++)
typedef long long ll;

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

    return 0;
}