#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using vi2 = vector<vector<int>>;
using vb = vector<bool>;
using vb2 = vector<vector<bool>>;
using vc = vector<char>;
using vc2 = vector<vector<char>>;
using vs = vector<string>;
using si = set<int>;
using vs2 = vector<vector<string>>;
using pii = pair<int, int>;
using mii = map<int, int>;
const int INF = 1e9;
const ll LINF = 1e18;
#define MP(a,b) make_pair((a),(b))
#define MT(...) make_tuple(__VA_ARGS__)

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,x) for(int i=0;i<(int)(x);i++)
#define REPS(i,x) for(int i=1;i<=(int)(x);i++)
#define RREP(i,x) for(int i=((int)(x)-1);i>=0;i--)
#define RREPS(i,x) for(int i=((int)(x));i>0;i--)

#define ALL(x) (x).begin(),(x).end()
#define IN(type,a) type a;cin >> a
#define YES(n) cout << ((n) ? "YES" : "NO"  ) << endl
#define Yes(n) cout << ((n) ? "Yes" : "No"  ) << endl
#define COUT(x) cout << (x) << endl
#define DCOUT(x,n) cout << fixed << setprecision(n) << (x) << endl

template<typename T>
T gcd(T x, T y){
    if ((x==1)||(y==1)) return 1;
    if (x>y) {
        if (x%y==0) {
            return y;
        }else{
            return gcd(y, x%y);
        }
    }else{
        if (y%x==0) {
            return x;
        }else{
            return gcd(x, y%x);
        }
    }
}

int main() {
    IN(int, s);
    IN(int, w);
    if (w>=s) {
        COUT("unsafe");
    }else{
        COUT("safe");
    }
}
