
#include <bits/stdc++.h>
#define Phuong_ ios_base::sync_with_stdio(0); cin.tie(0);

/// easy access -------------
using namespace std;
using ll = long long;
using ld = long double;
typedef pair<int,int> pii;
///-------------------------


int main()
{
    Phuong_; /// <3
    int a,b;
    cin >> a >>b;
    if (b>=a) cout << "unsafe"; else cout << "safe";
    return 0;
}
