#include <iostream>
#include <iomanip>
#include<vector>
#include <algorithm>
#include <queue>
#include<string>
#include <map>
#include <cmath>
#include <deque>
#include <list>
#include <stack>
#include <queue>
#include <utility>
#include <set>
#include <bitset>
typedef long long ll;
typedef long double ld;

#define REP(i,s,n)for(ll i=s;i<(n);++i)
#define rep(i,n) REP(i,0,n)
using namespace std;

int main() {
    int S, W;
    cin >> S >> W;

    if (S<=W) {
        cout << "unsafe" << endl;
    }
    else {
        cout << "safe" << endl;
    }

    return 0;
}