#include <algorithm>
#include <map>
#include <iostream>
#include <string>
#include <set>
#include <queue>
#include <cmath>
#include <iterator>
#include <array>
typedef long long int ll;
using namespace std;
#define maxN 1000005
#define mod 1000000007

ll all[maxN]= {};

void solve() {
	
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	int n,m;
	cin>>n>>m;
	if(n<=m){
		printf("unsafe\n");
	}else{
		printf("safe\n");
	}
}