#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const  ll INF = 1e9;
const  ll MOD = 1e9 + 7;
#define all(v) v.begin(), v.end()
#define repi(i,n,init) for(ll i=init;i<(n);i++)
#define repd(i,n,init) for(ll i=(n);i>=init;i--)
#define repm(i,m) for(auto i=m.begin();i!=m.end();i++)
#define repb(bit,n,init) for(ll bit=init;bit<(1<<n);++bit)

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