#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define MAX_INF 0x7f
#define MAX_INF_VAL 0x7f7f7f7f
#define pi 3.141592653589
#define eps 1e-10
//#define p 2173412051LL
//#define sz 2

using namespace std;

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