#include <bits/stdc++.h>
using namespace std;

// #define int long long

signed main()
{
    int i=0, j=0, k=0, ans=0;
    int S, W;
    cin>>S>>W;

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