#include<bits/stdc++.h>
#define LL long long
#define FOR(i,a,b) for(int i=a;i<=b;++i)
using namespace std;

const int mn=1e5+7;

int main()
{
	int a,b;
	scanf("%d%d",&a,&b);
	puts(b>=a?"unsafe":"safe");
}