#include <iostream> 
#include <string> 
#include <vector>
#include <algorithm>
#include <utility>
#include <tuple>
#include <cstdint>
#include <cstdio> 
#include <map> 
#include <queue> 
#include <set> 
#include <stack> 
#include <deque> 
#include <unordered_map> 
#include <unordered_set> 
#include <bitset> 
#include <cctype> 

using namespace std;
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define ll long long

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

