For den

package main

import (
    "fmt"
    "strconv"
)

func main() {
    //var num int64
    //fmt.Println(getSpreadsheetNotation(num))
    fmt.Println(getSpreadsheetNotation(27))
    fmt.Println(getSpreadsheetNotation(1405))
}

func getSpreadsheetNotation(a int64) string {

    var div702 int64 = a / 702
    var mod702 int64 = a % 702

    if mod702 != 0 {
        div702++
    } else {
        mod702 = 702
    }

    var div26 int64 = mod702 / 26
    var mod26 int64 = mod702 % 26

    if mod26 == 0 {
        mod26 = 26
        div26--
    }

    var firstLetter = string('A' - 1 + div26)
    var secondLetter = string('A' - 1 + mod26)

    if div26 == 0 {
        return strconv.FormatInt(div702, 10) + secondLetter
    } else {
        return strconv.FormatInt(div702, 10) + firstLetter + secondLetter
    }

}