#define ll long long
#define INF 99999999
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#include<bits/stdc++.h>
using namespace std;
int main (){
    int s,w;
    cin >> s>>w;
    if(s>w) cout << "safe" << endl;
    else cout << "unsafe" << endl;
    return 0;
}