valid = arr => {
  const [x1, y1, x2, y2] = arr;
  const result= []
  const a = Math.sqrt(x1 ** 2 + y1 ** 2);
  const b = Math.sqrt(x2 ** 2 + y2 ** 2);
  const c = Math.sqrt((y1 - y2) ** 2 + (x1 - x2) ** 2);

  const isValid = (a, x, y) =>
    a === Math.floor(a)
      ? result.push(`{${x}, ${y}} to {0, 0} is valid`)
      : result.push(`{${x}, ${y}} to {0, 0} is invalid`);

  isValid(a, x1, y1);
  isValid(b, x2, y2);

  c === Math.floor(c)
    ? result.push(`{${x1}, ${y1}} to {${x2}, ${y2}} is valid`)
    : result.push(`{${x1}, ${y1}} to {${x2}, ${y2}} is invalid`);
    return result.join('\n')
}