#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

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