#include<bits/stdc++.h>
#define ll long long
#define mp make_pair
#define pb push_back
#define F first
#define S second
#define mod 1000000007
#define fastio; ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
using namespace std;
typedef vector<ll> vll;
typedef vector<int> vi;



int main(){

    fastio;
    int s,w;
    cin>>s>>w;

    if(w>=s) cout<<"unsafe"<<endl;
    else cout<<"safe"<<endl;

    return 0;
}
