#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> P;
const ll mod = 1000000007;
const ll INF = mod * mod;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)

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