#include<bits/stdc++.h>

#define f first
#define s second
using namespace std;
typedef long long ll;
const ll minn=-1e9;
const ll limit = 1e6+2;
pair <ll,ll> a[limit];
pair <ll,ll> b[limit];
long long t,n,k,temp=0,m,res=0,tp,mp,op,check=1,lp,d=0,s,w;

int main()
{
    cin>>s>>w;
    if(s>w) cout<<"safe";else cout<<"unsafe";
}
