#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<=b;i++)
#define repr(i,a,b) for(int i=a;i>=b;i--)
#define ll long long int
using namespace std;
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    #ifndef ONLINE_JUDGE
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
    #endif
    int s;w; cin>>s>>w;
    if(w>=s)
        cout<<"unsafe\n";
    else
        cout<<"safe\n";

    return 0;
}