const Main = (input) => {
  const tmp = input.split(' ')
  const sheeps = parseInt(tmp[0])
  const wolves = parseInt(tmp[1])
  let result
  if (sheeps > wolves) {
    result = 'safe'
  } else {
    result = 'unsafe'
  }

  console.log(result)
  return result
}

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