

void main(){
	
	auto SW = readLine!size_t();
	if( SW[0] <= SW[1] ){
		writeln("unsafe");
	} else {
		writeln("safe");
	}
}


import std.stdio, std.string, std.conv;
import std.math, std.algorithm, std.array;
import std.regex;

T[] readLine( T = size_t )( string sp = " " ){
	T[] ol;
	foreach( string elm ; readln().chomp().split(sp) ){
		ol ~= elm.to!T();
	}
	return ol;
}