function Main(input) {
	var str = input;
	str = str.split("\n")[0];
    str = str.split(' ');
    s = str[0];
    w = str[1];
	if(s<=w){
  		console.log("unsafe");
	}else{
		console.log("safe");
	}
}
 //*おまじない
Main(require("fs").readFileSync("/dev/stdin", "utf8"));
