#include<bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define fst first
#define snd second
using namespace std;

typedef long long ll;
typedef double db;
typedef long double ldb;

template<class T> inline void checkmin(T &a,const T &b){if(b<a) a=b;}
template<class T> inline void checkmax(T &a,const T &b){if(b>a) a=b;}

const int inf=1e9+10;

int s,w; 

int main(){
	scanf("%d%d",&s,&w);
	if(s<=w) printf("unsafe\n");
	else printf("safe\n");
	return 0;
}
