#include <iostream>
#include <cstdio>
#include <set>
#include <list>
#include <vector>
#include <stack>
#include <queue>
#include <map>
#include <string>
#include <sstream>
#include <algorithm>
#include <cstring>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <fstream>
#include <iomanip>
//#include <unordered_map>
using namespace std;
#define dbg(x) cerr << #x " = " << x << endl;
typedef pair<int, int> P;
typedef long long ll;

int main()
{
    //freopen("in.txt", "r", stdin);
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int s, w;
    cin >> s >>w;
    if(s <= w)
    {
        cout << "unsafe" << endl;
    }
    else
    cout << "safe" << endl;
}