#pragma GCC optimize ("-O3")
#include <bits/stdc++.h>
#define pb push_back
#define pll pair<ll, ll>
#define mll map<ll, ll>
#define ff first
#define oo 1000000000000000005
#define ss second
#define el "\n"
#define maxS 100005
#define MOD 1000000007
using namespace std;
typedef long long ll;

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    // ll t;cin>>t;while(t--)
    {
        ll s, w;
        cin>>s>>w;
        if(w >= s)
            cout<<"unsafe\n";
        else
            cout<<"safe\n";
    }
    return 0;
}