#include <bits/stdc++.h>
#define _GLIBCXX_DEBUG
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = s; i < (int)(n); i++)
typedef long long ll;
typedef vector<vector<ll>> vvl;
typedef vector<ll> vl;
typedef vector<vector<char>> vvc;
typedef vector<char> vc;
typedef pair<ll,ll> pll;
typedef priority_queue<string> priquest;
typedef priority_queue<string,vector<string>,greater<string>> rpriquest;
ll max(ll x,ll y){
if(x>y)return x;
else return y;
}
ll min(ll x,ll y){
  return x+y-max(x,y);
}
ll lcm(ll l,ll a){
    return a/__gcd(l,a)*l;
}
ll exp(ll a, ll b,ll c){
  if(b==0)return 1;
  if(b%2==0){
    ll t =exp(a,b/2,c);
    return t*t%c;
  }
  else return exp(a,b-1,c)*a%c;
}
const ll big=1000000007;


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