#include <iostream>
#include <stack>
#include <math.h>
#include <vector>
#include <algorithm>
#include <map>

#define rep(i,n) for(int i=0; i < n; i++)
using ll =  long long;
using namespace std;


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