/*-- ILSH  --*/
#include "bits/stdc++.h"
using namespace std;
typedef long long int ll;
#define pb push_back 
#define pop pop_back
#define mp make_pair
#define vii vector < int >
#define vll vector < ll > 
#define pii pair < int , int >
#define pll pair < ll , ll >
#define vpi vector < pii >
#define vpl vector < pll >
#define fi first
#define se second 
#define sz size 
#define len length 

const ll mod = 1e9+7;
const ll inf=1e18+1e17;
//const ll mod = 998244353;

ll modInverse(ll a,ll m){ll m0=m;ll y=0,x=1;if(m == 1)return 0;while(a> 1){ll q=a/m;ll t=m;m=a%m,a=t;t=y;y=x-q*y;x=t;}if(x<0)x+=m0;return x;}  
ll powm(ll a,ll b){a=a%mod;ll res=1;while(b){if(b&1)res=(res*a)%mod;a=(a*a)%mod;b>>=1;}return (res%mod);}

const ll N=2e5+6;


void solve(){
	ll s,w;
	cin>>s>>w;
	if ( w>=s)
		cout<<"unsafe\n";
	else
		cout<<"safe\n";

}


int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
//	#ifndef ONLINE_JUDGE
	//  freopen ("INPUT.txt" , "r" , stdin);
	  //freopen ("OUTPUT.txt", "w" , stdout);
//	#endif	
    ll t=1;
	//cin>>t;
    for (int i=1;i<=t;i++){
    //	cout<<"Case #"<<i<<": ";
    	solve();
 	}
}



