#include <iostream>
using namespace std;
int main () {
	 //#ifndef ONLINE_JUDGE
    // for getting input from input.txt
    //freopen("input.txt", "r", stdin);
    // for writing output to output.txt
    //freopen("output.txt", "w", stdout);
   // #endif
	int a, b;

	cin>>a>>b;

    if (b >= a) {
    	cout << "UNSAFE" << endl;
    }
    else {
    	cout << "SAFE" << endl; 
    }


	return 0;
}