#include <bits/stdc++.h>
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define ll          long long
#define pb          push_back
#define eb 			emplace_back
#define mp 			make_pair
#define pii         pair<ll,ll>
#define vi          vector<ll>
#define vii         vector<pii>
#define mi          map<ll,ll>
#define mii         map<pii,ll>
#define all(a)      (a).begin(),(a).end()
#define fi          first
#define si          second
#define sz(x)       (ll)x.size()
#define endl        '\n'
#define checkbit(n, b) ((n >> b) & 1)
#define mod        1000000007
#define inf        1000000000000000000
#define puts(n)		cout<<n;
#define rep(i,a,b)  for(ll i=a;i<b;i++)
#define setbits(x) __builtin_popcount(x)
#define mset(m,v) memset(m,v,sizeof(m))
using namespace std;
int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	ll s,w;
	cin>>s>>w;
	if(w>=s) cout<<"unsafe";
	else cout<<"safe";
	
	return 0;
}