Barcode Generator

package main

import "fmt"

func main() {
    var startNum, finalNum int
    fmt.Scanln(&startNum)
    fmt.Scanln(&finalNum)

    for a := startNum / 1000; a <= finalNum / 1000; a++ {
        for b := startNum / 100 % 10; b <= finalNum / 100 % 10; b++ {
            for c := startNum / 10 % 10; c <= finalNum / 10 % 10; c++ {
                for d := startNum % 10; d <= finalNum % 10; d++ {
                    if a % 2 == 1 && b % 2 == 1 && c % 2 == 1 && d % 2 == 1 {
                        fmt.Printf("%d%d%d%d ", a, b, c, d)
                    }
                }
            }
        }
    }
}

ИЛИ:

package main

import "fmt"

func main() {
    var startNum, finalNum string
    fmt.Scanln(&startNum)
    fmt.Scanln(&finalNum)

    for a := startNum[0]; a <= finalNum[0]; a++ {
        for b := startNum[1]; b <= finalNum[1]; b++ {
            for c := startNum[2]; c <= finalNum[2]; c++ {
                for d := startNum[3]; d <= finalNum[3]; d++ {
                    if a % 2 == 1 && b % 2 == 1 && c % 2 == 1 && d % 2 == 1 {
                        fmt.Printf("%c%c%c%c ", a, b, c, d)
                    }
                }
            }
        }
    }
}