#include <bits/stdc++.h>
#include <ext/numeric>

using namespace std;
using namespace __gnu_cxx;

#define all(v)   v.begin(), v.end()
#define UNIQUE(c) (c).resize(unique(all(c)) - (c).begin())
#define endl "\n"
#define pb push_back
#define F first
#define S second
#define START cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
#define isOdd(n)    (n&1)
#define LLMAX LLONG_MAX
#define LLMIN LLONG_MIN
#define IMN INT_MIN
#define IMX INT_MAX
#define pow(n, m) power((ll)n, (ll)m)
#define numOfDigits(n)  ((n)? (ll)(log10(n))+1 : 1)
#define mem(x, val)    memset(x, val, sizeof(x)) //be careful
#define var auto
#define MOD 1000000007


typedef long long ll;
typedef long double ld;
typedef double dd;
typedef pair<int, int> pii;


int main()
{
    START
    //freopen("test cases\\in.txt", "r", stdin) ;
    int w, s; cin>>s>>w;
    cout<<(w>=s?"unsafe":"safe");
	return 0;
}
