#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define FAST ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);srand(time(NULL));
#define MOD 1000000007
#define INF LONG_LONG_MAX
#define MINF LONG_LONG_MIN


void init(){
}

ll po(ll x, ll y) { 
    ll res = 1;
    while (y > 0) { 
        if (y & 1) 
            res = (res*x)%MOD; 
        y = y>>1;  
        x = (x*x)%MOD;
    } 
    return res; 
}



void solve(){
    ll s,w;
    cin>>s>>w;
    if( s > w ) cout<<"safe"<<endl;
    else cout<<"unsafe"<<endl;
    return;
}

int main(){
    FAST;
    init();
    ll t = 1;
    //cin>>t;
    while( t-- ) solve();
    return 0;
} 