开始-区分仅数字的用户输入和其他所有内容

I am trying to get the code to loop if the number entered is below 600 and to loop if the input contains letters and symbols. I just cannot do it.

package main

import (
    "fmt"
    "strconv"
)


func main() {
    fmt.Println("How far in metres are the people away from the spacecraft?")
    var people string
    fmt.Scanf("%s",&people)
      number, _ := strconv.Atoi(people)
      for number < 600 {
        if (number < 0 || number > 0 || people == "0"){
          fmt.Println("Too Close
Try Again")
        var people string
        fmt.Scanf("%s",&people)
        number, _ := strconv.Atoi(people)
            fmt.Println(number)
          }else{
            fmt.Println("Only Number Please
Try Again")
          var people string
          fmt.Scanf("%s",&people)
          number, _ := strconv.Atoi(people)
            fmt.Println(number)
            }

      }

fmt.Println("BLAST OFF !!!")
}

eugenioy and Chrono Kitsune are correct.
To clarify what they are saying in code, here is an example:

var people string
var err error
var number int
for {
    fmt.Scanf("%s",&people)
    number, err = strconv.Atoi(people)
    if err == nil {
        break
    }
    fmt.Println("Not a number, please try again")
}
fmt.Println(number)