#include <iostream>
#include <algorithm>
#include <bitset>
#include <math.h>
#include <string>
#include <map>
#include <vector>
using namespace std;
using ll = long long;
using ull = unsigned long long;
#define rep(i, n) for (int i = 0; i < n; i++)
#define LargeNum 1000000007
typedef pair <double, double> P;

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