//Say hi to nerdy_geek2799
//work untill your role model does not become your opponent

#include<bits/stdc++.h>
#define endl "\n"
#define ll long long int
#define MOD 1000000007
#define mp make_pair
#define pll pair<ll,ll>
#define pb push_back
#define all(v) (v.begin(),v.end())
#define Ryo ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define rep(i,a,b) for(long long int i=a;i<b;i++)
#define nrep(i,a,b) for(long long int i=a;i>=b;i--)
#define ceil(a,b) a/b+((a%b ==0 )?0:1)
using namespace std;
int main()
{
    Ryo;
    

    ll s,w;
    cin>>s>>w;
    if(w>=s)
    {
        cout<<"unsafe";
    }
    else
        cout<<"safe";
}
