/*ctrl+shift+D =?repeat line
ctrl+x delete a line
*/
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;

#define ff              first
#define ss              second
#define int             long long
#define pb              push_back
#define mp              make_pair
#define pii             pair<int,int>
#define vi              vector<int>
#define mii             map<int,int>
#define pqb             priority_queue<int>
#define pqs             priority_queue<int,vi,greater<int> >
#define setbits(x)      __builtin_popcountll(x)
#define zrobits(x)      __builtin_ctzll(x)
#define mod             1000000007
#define inf             1e18
#define ps(x,y)         fixed<<setprecision(y)<<x
#define mk(arr,n,type)  type *arr=new type[n];
#define w(x)            int x; cin>>x; while(x--)
mt19937                 rng(chrono::steady_clock::now().time_since_epoch().count());

typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;


void c_p_c()
{
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#ifndef ONLINE_JUDGE
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
}



int32_t main()
{
	c_p_c();
	//string s;
	//cout << "Enter string:";
	//cin >> s;
	int a, b;

	cin >> a >> b;
	if (b >= a) {
		cout << "unsafe\n";
	}
	else
	{
		cout << "safe\n";
	}
	//char a[101];

	/*if (strstr(a, "100001") || strstr(a, "10001") || strstr(a, "1001") || strstr(a, "101") || strstr(a, "11") || strstr(a + 5, "100001") || strstr(a + 4, "10001") || strstr(a + 3, "1001") || strstr(a + 2, "101") || strstr(a + 1, "11"))
		printf("NO\n");
	else
		printf("YES\n"); */

	return 0;



}