#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll read(){
	ll a=0,b=getchar(),c=1;
	while(!isdigit(b))c=b=='-'?-1:1,b=getchar();
	while(isdigit(b))a=a*10+b-'0',b=getchar();
	return a*c;
}
int a,b;
int main(){
	a=read(),b=read();
	if(a>b)puts("safe");
	else puts("unsafe");
	return 0;
}