#include<iostream>
#include<vector>
#include<cstdio>
#include<string>
#include<algorithm>
#include<map>
#include<set>
#include<cmath>
#include<deque>
using namespace std;

using ll = long long;
const int INF = 1001001001;
const ll LLINF = 1001001001001001001;
const int MOD = 1000000007;

#define rep(i,n) for (int i = 0; i < (n); ++i)

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