function Main(input) {
  const lines = input.split(' ').map(e => parseInt(e));
  let sh = lines[0];
  let wol = lines[1];
  if ( sh > wol ) {
    console.log("safe");
  } else {
    console.log("unsafe");
  }
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));