#include <bits/stdc++.h>
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define rep2(i,a,n) for(int i=a;i<n;i++)
#define been(ix) (ix).begin(),(ix).end()
using namespace std;
typedef long long ll; 
typedef vector<int> vi;
typedef vector<long long> vl;
const ll INFL = 1e18;
const int INF = 1001001001; 
typedef pair<int,int> P;
#define foreach(ix,i) for(auto& (ix) : (i))
typedef long double ld;
const int mod =1000000007;
int main(){
    int a,b;
    cin>>a>>b;
    if(a<=b)cout<<"unsafe"<<endl;
    else cout<<"safe"<<endl;
}