function singleNumber(numbers: number[]): number {
  let obj = {}
  let arr = []
  for(let i of numbers) {
    !obj[i]? obj[i] = 1: obj[i] += 1;
  }

  arr = Object.entries(obj).filter((arr) => arr[1] === 1)[0];
  
  return +arr[0]
}

// No modificar: necesario para evaluar el resultado.
export { singleNumber };