const Main = input => {
  const inp = input.split(" ");
  const hitsujiNum = parseInt(inp[0], 10);
  const ookamiNum = parseInt(inp[1], 10);
  
  if(hitsujiNum <= ookamiNum) {
    console.log("unsafe");
  } else {
    console.log("safe");
  }
}
 
Main(require("fs").readFileSync("/dev/stdin", "utf8"));