#include <cstdio> 
#include <cstdlib> 
#include <cmath> 
#include <cstring> 
#include <climits> 
#include <cfloat> 
#include <map> 
#include <utility> 
#include <set> 
#include <iostream> 
#include <memory> 
#include <string> 
#include <vector> 
#include <algorithm> 
#include <functional> 
#include <sstream> 
#include <complex> 
#include <stack> 
#include <queue> 
#include <numeric>
#include <cassert>

#define FOR(i, min, max) for (int i = (min); i < (max); ++i) 
#define FORE(i, min, max) for (int i = (min); i <= (max); ++i) 
#define REP(i, n) for (int i = 0; i < (n); ++i) 
#define REPV(vec, i) for (int i = 0; i < (int)(vec.size()); ++i) 
#define FOR_EACH(vec, it) for (typeof((vec).begin()) it = (vec).begin(); it != (vec).end(); ++it)

using namespace std; 
static const double EPS = 1e-12; 
typedef long long ll; 

template<typename T>
vector<T> getVector(int N) {
    vector<T> v(N);
    REP(i, N) cin >> v[i];
    return v;
}

int main(void)
{
    int S, W;
    cin >> S >> W;
    if (S <= W)
        cout << "unsafe" << endl;
    else
        cout << "safe" << endl;
    return 0;
}
