#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)n;++i)
#define REP(i,a,b) for(int i=int(a);i<(int)b;++i)


using namespace std;
using ll = long long;

int main(void)
{
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
    int s ,w;
    cin >> s >> w;
    if(s<=w)cout << "unsafe" << endl;
    else cout << "safe" << endl;
   
   

    return 0;
}
