Keep reading Command-line until you get the word END
takes (integers) numbers from Command-line and keeps reading the
  terminal until it gets a word END.




For example,

package main

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

func main() {
    sum := int64(0)
    s := bufio.NewScanner(os.Stdin)
    s.Split(bufio.ScanWords)
    for s.Scan() {
        word := s.Text()
        num, err := strconv.ParseInt(word, 10, 64)
        if err != nil {
            if strings.ToUpper(word) == "END" {
                break
            }
            fmt.Fprintln(os.Stderr, err)
            continue
        }
        sum += num
    }
    if err := s.Err(); err != nil {
        fmt.Fprintln(os.Stderr, err)
    }
    fmt.Println("Sum of all numbers:", sum)
}


Terminal:

12 24 
36 
6
6
  END
Sum of all numbers: 84