#!/usr/bin/env node

function getDigitFromRight(numberString, indexFromRight) {
  if (indexFromRight < 0) {
    throw new Error('you should not be here')
  }
  if (indexFromRight >= numberString.length) {
    return 0
  }
  return parseInt(numberString[numberString.length - 1 - indexFromRight])
}

// test('getDigitFromRight', () => {
//   expect(getDigitFromRight('649', 0)).toBe(9)
//   expect(getDigitFromRight('649', 1)).toBe(4)
//   expect(getDigitFromRight('649', 2)).toBe(6)
// })
// test('return 0 when out of range', () => {
//   expect(getDigitFromRight('649', 3)).toBe(0)
// })

function add(a = '' /*string*/, b = '' /*string*/) {
  let longNumberString = a
  let shortNumberString = b
  if (b.length > a.length) {
    longNumberString = b
    shortNumberString = a
  }

  let carry = 0
  let answer = ''

  for (let index = 0; index < longNumberString.length; index++) {
    const upDigit = getDigitFromRight(longNumberString, index)
    const downDigit = getDigitFromRight(shortNumberString, index)

    const digitSum = upDigit + downDigit + carry
    answer = (digitSum % 10).toString() + answer
    carry = Math.floor(digitSum / 10)
  }

  if (carry !== 0) {
    answer = carry.toString() + answer
  }

  return answer
}

// test('add', () => {
//   expect(add('0', '0')).toBe('0')
//   expect(add('0', '2')).toBe('2')
//   expect(add('1', '2')).toBe('3')
//   expect(add('10', '2')).toBe('12')
//   expect(add('10', '200')).toBe('210')
//   expect(add('96', '4')).toBe('100')
//   expect(add('960700081327001', '43520069100001')).toBe('1004220150427002')
// })
// test('add big int', () => {
//   expect(add('9007199254740991', '9007199254740991')).toBe('18014398509481982')
//   expect(add('9007199254740991', '9007199')).toBe('9007199263748190')
//   expect(add('9007199254740991', '90071992547409919007199254740991')).toBe('90071992547409928014398509481982')
// })

const args = process.argv.slice(2)
console.log(add(args[0], args[1]))