#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <queue>
#include <unordered_map>
#include <map>
#include <limits.h>
#include <unordered_set>
#include <stack>
#include <string.h>
#include <math.h>
#define fo(i,l,r) for(int i=l;i<=r;++i)
#define fi(i,r,l) for(int i=r;i>=l;--i)
#define pb push_back
#define po pop_back
#define speed ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
typedef long long int ll;
typedef unsigned long long int ulli;
using namespace std;
void generatePrimes(){

}
void swap(int *a,int *b){
    int tmp = *a;
    *a = *b;
    *b = tmp;
}
void input(vector<int>& arr,int n){
    fo(i,0,n-1){
        cin>>arr[i];
    }
}
void input(vector<ll>& arr,int n){
  fo(i,0,n-1){
    cin>>arr[i];
  }
}
void input(vector<ulli>& arr,int n){
    fo(i,0,n-1){
        cin>>arr[i];
    }
}
ll max(ll a,ll b){
    return a>b?a:b;
}
ulli max(ulli a,ulli b){
    return a>b?a:b;
}
int max(int a,int b){
    return a>b?a:b;
}
void print(vector<int>& ans,int n){
    fo(i,0,n-1){
        cout<<ans[i]<<" ";
    }
    cout<<endl;
}
void print(vector<ll>& ans,int n){
    fo(i,0,n-1){
        cout<<ans[i]<<" ";
    }
    cout<<endl;
}
void solve(){
    ll s,w;
    cin>>s>>w;
    if(w>=s){
      cout<<"unsafe"<<endl;
    }
    else{
      cout<<"safe"<<endl;
    }
}
int main(){
    speed;
    solve();
}
