#define _USE_MATH_DEFINES
#include <math.h>
#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <algorithm>
#include <queue>

using namespace std;
typedef long long ll;

#define rep(i, n) for(ll i = 0; i < (ll)(n); i++)

int main() {

    ll S,W;
    cin >> S >> W;
    string out = "unsafe";
    if(S>W) out = "safe";
    cout << out << endl;
    return 0;
}
