function solve (arr) {
  let sum = arr.map(Number).reduce((a, b) => a + b, 0)
  let maxElement = +Math.max(...arr)
  let diff = Math.abs(sum - maxElement * 2)
  console.log(diff === 0 ? `Sum = ${maxElement}` : `No, Diff = ${diff}`)
}

solve(['2', '10', '90', '60', '40'])