#include <iostream>
#include <iomanip>
#include <algorithm>
using namespace std;
#include <cstdio>
#include <tuple>
#include <string>
#include <vector> 
#include <set>
#include <string.h>
#include <map>
#include <cmath>
#include <deque>
using ll = long long;
using Graph = vector<vector<int>>;
#include <queue>
#include <stack>
#include <math.h>  /* M_PI */

const ll MOD = 1000000007;
int main(){

    int s,w;
    cin >> s >> w;
    if(w >= s) cout << "unsafe" << endl;
    else cout << "safe" << endl;
    return 0;
}