#include <iostream>
#include <vector>
#include <string>
#include <algorithm>

using namespace std;

namespace Mylib{

}
int main(void){
    int S,W;
    
    cin >> S >> W;
    
    if(S>W){
        cout << "safe" << endl;
    }else{
        cout << "unsafe" << endl;
    }
    return 0;


}
