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

#define ll long long
#define mod 1000000007
#define pb push_back
#define pi pair<int,int>
#define vi vector<int>
#define vpi vector< pi > 
#define IOS ios_base::sync_with_stdio(false),cin.tie(NULL)
const int N=100003,M=5002;

int main()
{
    int a,b;
    cin>>a>>b;
    if(a<b) cout<<"unsafe";
    else cout<<"safe";
    return 0;
}