#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> ii;
typedef pair<ld,ld> id;
typedef tuple<ll,ll,ll> tl;
typedef tuple<ll,ll,ll,ll> ql;

#define FOR(i, a, b) for(ll i=(a); i<=(b); i++)
#define ROF(i, a, b) for(ll i=(a); i>=(b); i--)
#define MEM(x, v) memset(x, v, sizeof(x))
#define FILL(x, n, v) fill(x, x+n, v);
#define ALL(x) x.begin(), x.end()
#define FAST ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);

#define f first
#define s second
#define ins insert
#define e emplace
#define eb emplace_back
#define ef emplace_front
#define p push
#define pf push_front
#define pb push_back
#define mp make_pair
#define ub upper_bound
#define lb lower_bound
#define ft front
#define bk back
#define pp pop
#define ppb pop_back
#define ppf pop_front

#define db cout<<"YEET\n";
#define ct(x) cout<<x<<'\n';

const ll MOD = 1e9+7; //998244353
const ll MAXN = 10+5;
const ll INF = 1e18;
const ld PI = acos((ld)-1);

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