#include <bits/stdc++.h>
using namespace std;
#define REP(i, n) for(int i = 0; i < n; i++)
#define REPR(i, n) for(int i = n; i >= 0; i--)
#define FOR(i, m, n) for(int i = m; i < n; i++)
#define ALL(v) v.begin(), v.end()
#define CMAX(m, x)  m = max(m,x);
#define CMIN(m, x)  m = min(m,x);
#define itn int
typedef long long lint;
const int INF = 1e9;
const lint LINF = 1e18;
int main(){
    int s,w;
    cin >> s >> w;
    if(s > w)
        cout << "safe" << endl;
    else
        cout << "unsafe" << endl;
    return 0;
}