#include <bits/stdc++.h>
using namespace std;
 
#define ll long long
#define fi first
#define se second
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define rep1(i, n) for (int i = 1; i <= (int)(n); ++i)
#define rep11(i, n) for (int i = 1; i < (int)(n); ++i)
#define rep0(i, n) for (int i = 1; i <= (int)(n); ++i)
#define repo(i, o, n) for (int i = o; i < (int)(n); ++i)
#define repm(i, n) for (int i = (int)(n)-1; i >= 0; --i)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define pb(n) push_back(n)
#define mp make_pair
#define MOD 1002000007
#define INF LO

int main(){
    int s,w;
    cin>>s,w;
    if (s>=w){
        cout<<"unsafe"<<endl;
    }
    else{
        cout<<"safe"<<endl;
    }
    return 0;
}