#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <cstring>
#include <math.h>
#include <bitset>
#include <queue>
#include <set>
#include <iomanip>
#include <assert.h>
#include <cstdio>
// #include<bits/stdc++.h>
using namespace std;
typedef long long ll;
constexpr long long int INFLL = 1001001001001001LL;
constexpr long long int infll = 1001001001001001LL;
constexpr int INF = 1000000007;
constexpr int inf = 1000000007;
const int mod = 1000000007;

//----------------------------------------------------------------

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