Envío 5053

Código

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func main() {
	reader := bufio.NewReader(os.Stdin)

	number, _ := reader.ReadString('\n')
	number = strings.ReplaceAll(number, "\n", "")
	digitS, _ := reader.ReadString('\n')
	digitS = strings.ReplaceAll(digitS, "\n", "")
	digit, _ := strconv.ParseInt(digitS, 10, 64)
	out := []rune(number)
	sum := true
	index := len(number) - 1
	for sum && index >= 0 {
		numberIndex, _ := strconv.ParseInt(string(out[index]), 10, 64)
		numberIndex += digit
		digit = 1
		if numberIndex > 9 {
			number := fmt.Sprintf("%d", numberIndex)
			out[index] = []rune(number)[1]

			if index == 0 {
				out = append([]rune("1"), out...)
			}
			index--
		} else {
			out[index] = []rune(fmt.Sprintf("%d", numberIndex))[0]
			sum = false
		}
	}

	fmt.Println(string(out))
}