#include<bits/stdc++.h>
using namespace std;
#define ll long long
using P = pair<ll, ll>;
#define rep(i, n) for(int i=0;i<(int)n;i++)
#define PI acos(-1)
#define fast_io ios_base::sync_with_stdio(false) ; cin.tie(0); cout.tie(0);
ll mod=1e9+7;


int main(){
    fast_io

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

    if(w>=s) cout<<"unsafe"<<endl;
    else cout<<"safe"<<endl;
    
    return 0;
}