// JAI SHREE RAM
typedef long long int ll;
typedef unsigned long long int ull;
#define fast  ios_base::sync_with_stdio(false); cin.tie(NULL);
#define FOR(i,n) for(int i=0;i<n;i++)
#define MOD 1000000007
#define sz(a) int((a).size())
#define forn(i, n) for (int i = 0; i < (n); ++i)
#define fore(i, l, r) for (int i = int(l); i < int(r); ++i)
#define loop for(int i=0;i<n;i++)
#define max3(a,b,c) max(a,max(b,c))
#define max4(a,b,c,d) max3(a,max(b,c),d)
#define max5(a,b,c,d,e) max4(a,max(b,c),d,e)
#define min3(a,b,c) min(a,min(b,c))
#define min4(a,b,c,d) min3(a,min(b,c),d)
#define min5(a,b,c,d,e) min4(a,min(b,c),d,e)
#define sec second
#define fir first
// #define all(a) (a).begin(),(a).end()
#define vec vector<int>
#define M_PI           3.14159265358979323846  /* pi */
#define pb push_back
#define pii pair<int,int>
#include<bits/stdc++.h>
#include<cmath>
using namespace std;
int main()
{
	ll s,w;
	cin>>s>>w;
	if(w>=s)
		cout<<"unsafe";
	else
		cout<<"safe";
}