#include<bits/stdc++.h>
#define ll long long
#define pb push_back
#define pii pair < int, int >
#define pll pair < ll, ll >
using namespace std;

int main()
{
    int s, w;

    cin >> s >> w;

    if(w >= s) cout << "unsafe" << endl;
    else cout << "safe" << endl;

    return 0;
}
