#define _USE_MATH_DEFINES
#include <iostream>
#include <fstream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <cassert>
#include <string>
#include <vector>
#include <utility>
#include <complex>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <deque>
#include <tuple>
#include <bitset>
#include <limits>
#include <algorithm>
#include <array>
#include <random>
#include <complex>
#include <regex>
using namespace std;
typedef long double ld;
typedef long long ll;
typedef vector<int> vint;
typedef vector<ll> vll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define fcout cout << fixed << setprecision(10)
#define rep(i,n)    for(int i=0; i<(int)n; i++)
#define mp(a,b) make_pair(a,b)
#define pb push_back
const ll inf = 1e18;
const ll mod = 1e9 + 7;

ll pow (ll x, ll n){
    ll ans = 1;
    while(n>0){
        if(n & 1 == 1){
            ans *= x;
        }
        x = x * x;
        n >>= 1;
    }
    return ans;
}


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