#include <bits/stdc++.h>
using namespace std;
#define rep(i, m, n) for(int i=m; i<n; i++)
typedef long long ll;
typedef pair<int, int> P;
typedef pair<ll, ll> Pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vll;
template <typename T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1;} return 0; }
template <typename T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1;} return 0; }


int main() {
    int n,m; cin>>n>>m;
    if(n<=m) cout<<"unsafe"<<endl;
    else cout<<"safe"<<endl;

}