import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;

/**
 * PingMailDomain.java
 * @author jileniao.net
 * 判断输入的邮件地址@后的域名是否正确
 */
public class PingMailDomain {

    private Boolean isMailDomailRight(String emailAdd) throws IOException {
        String[] tmp = emailAdd.split("@");
        
        // 简单校验邮件地址是否含有@号：非有效邮箱地址
        if (!emailAdd.contains("@")) {
            return false;
        }
        String domain = tmp[1];
        String cmdString = "cmd /c ping " + domain;
        Process prs = Runtime.getRuntime().exec(cmdString);
        BufferedReader br = new BufferedReader(new InputStreamReader(prs.getInputStream()));

        String line = null;
        StringBuffer sb = new StringBuffer();
        // 得到ping结果信息
        while ((line = br.readLine()) != null) {
            sb.append(line);
        }

        String result = sb.toString();
        String[] temp = result.split("%");
        String result1 = temp[0];

        // ping结果loss为100%：非有效邮箱域名
        if (result1.endsWith("100")) {
            return false;
        }
        return true;
    }
    
    public static void main(String[] args) throws Exception {
        
        System.out.println("Please input EmailAddress");
        Scanner input = new Scanner(System.in);
        // 获取键盘输入的邮件地址
        String addressString = input.nextLine();
        PingMailDomain pmd = new PingMailDomain();
        if (pmd.isMailDomailRight(addressString)) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
    }
}