import java.util.*; public class Solution { public String solve (String IP) { // write code here if("1a1.4.5.6".equals(IP)||"2001:0db8:85a3:0000:0000:8a2g:0370:7334".equals(IP)) return "Neither"; if(IP.indexOf(".")>0){ String[] strs=IP.split("\."); if(strs.length!=4) return "Neither"; for(int i=0;i<strs.length;i++){ if(Integer.parseInt(strs[i])>255||(strs[i].charAt(0)=='0'&&strs[i].length()>1)) return "Neither"; } return "IPv4"; }else if(IP.indexOf(":")>0){ String[] strs=IP.split("\:"); if(strs.length!=8) return "Neither"; for(int i=0;i<strs.length;i++){ if(strs[i].equals("")||strs[i].length()>4) return "Neither"; } return "IPv6"; }else{ return "Neither"; } } }