#include<bits/stdc++.h>
#define fastio std::ios_base::sync_with_stdio(false), std::cout.tie(0), std::cin.tie(0);
#define N 100007
#define mxx INT_MAX

typedef long long ll;

int main(){
	int num1,num2;
	std::cin>>num1>>num2;
	if(num2>=num1)std::cout<<"unsafe";
	else std::cout<<"safe";
}